Belle Lake, Ireland Belle Lake (52 11'N, 7 02'W, 33m above sea level) is a shallow lake with area 45ha. The southern half of the basin is infilled and covered by reed-beds (Craig, 1978). The catchment area is ca 200ha. The area is generally covered by glacial drift thought to be from the penultimate glaciation, since Belle Lake lies over 30km from the limits of the last (Midlandian) glacial maximum (Colhoun and Mitchell, 1971). Old Red Sandstone outcrops as a low escarpment to the south-east of the basin. The basin probably originated as an erosion depression. A single 9m core taken from the northern edge of the reed-beds, to the south of the open-water area, provides a sedimentary record back to ca 12300 yr B.P. (Craig, 1978). The lake level changes are based on changes in lithology, aquatic pollen assemblages and sedimentation rates. The chronology is based on eight radiocarbon dates (Craig, 1978; Dresser and McAulay, 1974). The basal sediment (900-570cm) is grey clay. It contains very few aquatics. A sample from the overlying unit has been radiocarbon dated to 12235±260 yr B.P. (D-110). This pure clay might imply a deep water before ca 12300 yr B.P. The overlying sediments (570-520cm) are black gyttja, suggesting that the lake was low. The aquatic assemblage is characterised by Sparganium, Ranunculus, Potamogeton and Littorella. This suite and particularly the presence of Littorella is consistent with shallow conditions. The overlying sediment is grey clay (520-420cm), which could indicate an increase of water depth. Brown gyttja (420-390cm) overlies the grey clay, suggesting a return to shallow water. There is no difference in the aquatic assemblages between the black gyttja, grey clay and brown gyttja. The occurrence of clay could be due to increased erosion. We interpret the evidence as showing shallow water between ca 12300 and 9400 yr B.P. Two samples from black gyttja and grey gyttja have been radiocarbon dated to 10590±185 yr B.P. (D-111, 514-524cm) and 9600±135 yr B.P. (D-112, 396- 406cm) respectively. The sediment between 390 and 290cm is brown detritus gyttja. Nymphaea appears and reaches maximum abundance. The changes in the lithology and the aquatic assemblage suggest quite shallow water. Two samples from near the base and top of this unit have been radiocarbon dated to 9100±130 yr B.P. (D-113, 380-390cm) and 7373±105 yr B.P. (D-114, 290-300cm) respectively. The overlying unit (290-280cm) is diatomite. The aquatics are characterised by very high percentage Isoetes (ca 40%) with Potamogeton and Nymphaea, suggesting an increase in water depth between ca 7400 and 7000 yr B.P. Craig (1978) suggests that there might be a depositional hiatus around 280cm, since the sedimentation rate for the diatomite is very low (0.02 cm/yr). Abrupt changes in the terrestrial pollen (Alnus, Quercus and Pinus) and of pollen concentration are consistent with an hiatus. Extrapolation from sedimentation rates in the overlying peat gyttja (0.08 cm/yr) and underlying detritus gyttja (0.05 cm/yr) suggests the hiatus could span the interval ca 7000-6400 yr B.P. The overlying sediment is peaty gyttja (280-220cm). The aquatics include abundant Isoetes with other taxa such as Nymphaea, Potamogeton and Sparganium, suggesting intermediate water depth. Two samples from this unit have been radiocarbon dated to 6315±110 yr B.P. (D-115, 265-275cm) and 5720±90 yr B.P. (D-116, 220-230cm) respectively. The uppermost sediment is wood peat (220-180cm) with less aquatics, suggesting shallowing and infilling after ca 5700 yr B.P. There is a radiocarbon date of 5490±95 yr B.P. from the wood peat (D-117, 180-190cm). Peat from the uppermost 180cm was not recovered, but we assume that peat deposition continues to the present. The presence of peat reflects the hydroseral development in the basin. In the status coding: a possible hiatus is indicated by 0; low (1) by detritus gyttja with abundant Nymphaea; intermediate (2) by gyttja or clay with Sparganium, Ranunculus, Potamogeton and Littorella; high (3) by diatomite with very high abundance of Isoetes; or by pure clay without aquatics. The interval of peat deposition after ca 5700 yr B.P. is assumed to reflect hydroseral development and infilling of the basin and is not included in the coding. Radiocarbon dates D-117 5490±95 180-190cm, Wood peat D-116 5720±90 220-230cm, Peaty gyttja D-115 6315±110 265-275cm, Peaty gyttja D-114 7375±105 290-300cm, Detritus gyttja D-113 9100±130 380-390cm, Detritus gyttja D-112 9600±135 396-406cm, Transitional gyttja D-111 10590±185 514-524cm, Black gyttja D-110 12235±260 564-574cm, Black gyttja References Colhoun, E.A. and Mitchell, G.F. 1971. Interglacial marine formation and late glacial freshwater formation in Shortalstown, Co. Wexford. Proceedings of the Royal Irish Academy 71B: 211-245. Craig, A.J., 1973. Studies on the Ecological History of South-east Ireland, Using pollen influx analysis and other methods. Unpublished Ph.D. thesis, University of Dublin. Craig, A.J., 1978. Pollen percentage and influx analysis in South-east Ireland: A contribution to the ecological history of the Late-glacial period, Journal of Ecology 66: 297-324. Dresser, P.Q. and McAulay, I.R., 1974. Dublin radiocarbon dates II. Radiocarbon 16: 6-9. Coding ?-12300 yr B.P. probably high (3) 12300-9400 yr B.P. intermediate (2) 9400-7400 yr B.P. low (1) 7400-7000 yr B.P. high (3) 7000-6400 yr B.P. probable hiatus (0) 6400-5700 yr B.P. intermediate (2) 5700-0 yr B.P. infilling, not coded. Preliminary coding: 27/4/1993; Final coding: 21/7/1993. Coded by SPH and GY Cannons Lough, Ireland Cannons Lough (54 55'N, 6 35'W, ca 30m above sea level) is one of several small lakes which lie between esker ridges in the Lower Bann Valley, approximately midway between Lough Neagh and the north coast. There are glacial sands and gravels around Cannons Lough. The water depth is less than 2m and the area is ca 5ha. More than half of the lake is overgrown by reeds and floating mat vegetation (mainly Typha latifolia). The stratigraphy of sediments was reconstructed from a transect of ca 15 borings across the basin (Smith, 1961). There are two cores: core I (ca 10.5 long) was taken from the centre of the lake; core II (ca 6m long) from the nearshore. They provide a sedimentary record back to ca 11700 yr B.P. (Smith, 1961). Pollen analysis has been made on the basal part of in core I (ca 5-8m deep) and the upper part of core II (ca 1-4.5m). Lake level changes are reconstructed from changes in stratigraphy shown in the transect and the cores, and aquatic pollen assemblages. The chronology is based on pollen correlation with the nearby sites of Fallahogy and Toome Bay which are radiocarbon dated (Smith, 1970; Deevey, 1976). Core I bottoms out on gravels. The basal sediment in core I (1030-800cm) and core II (below 624cm) is silty clay with occasional coarse sand. No pollen analysis was carried out on this unit. The unit is more than 2m thick and is found over the whole of the basin, suggesting that the lake was quite large before ca 11700 yr B.P. The overlying sediment consists of silty clay mud in core I (800-720cm) or clay mud in core II (624-562cm). This layer lenses out towards the lake margin, suggesting that the lake was low when the unit was formed. The aquatic assemblage is characterised by abundant Littorella with some Potamogeton and Myriophyllum, consistent with shallow water. This shallow-water interval is dated to ca 11700-10500 yr B.P. The overlying sediment in core I (720-620cm) and core II (562-473 cm) is silty clay with very few aquatics such as Potamogeton and Myriophyllum. Littorella is absent. The unit is found right across the basin, indicating that the lake was larger than formerly. The lithology and paucity of aquatics are consistent with deep water. This period is dated to ca 10500-10300 yr B.P. The overlying sediments are clay mud (620-590cm in core I and 473-421cm in core II), suggesting shallower conditions. This layer becomes very thin towards the lake margins, and there are abundant rootlets in core II, both of which are consistent with shallowing. The aquatic assemblage is characterised by high percentages of Myriophyllum (ca 20%) with Littorella and Potamogeton, consistent with shallow water after ca 10300 yr B.P. The overlying sediments are fine detritus mud (590-0cm in core I and 421-250cm in core II). The aquatic assemblage in 590-500cm of core I is characterised by maximum abundance of Littorella, with decreasing Potamogeton and Myriophyllum. The abundance of Littorella suggest the lake became shallower after ca 9950 yr B.P. The overlying units in core I can be correlated with those in core II by the terrestrial pollen assemblages (Smith, 1961). Towards the uppermost part of core II, the sediments are coarse detritus mud (250-35cm). The lake gradually became infilled after ca 9000 yr B.P. The top of sediment in core II (35-0cm) is modern litter and rootlets. In the status coding: low (1) is indicated by fine detritus mud with maximum Littorella; intermediate (2) by clay mud that does not extend to the lake margins, and abundant Littorella; high (3) by clay mud that extends to the lake margins, and some Littorella, Potamogeton and Myriophyllum; very high (4) by silty clay with very few aquatics of Myriophyllum. The interval after 9000 yr B.P. is not coded because the sequence appears to reflect infilling. Radiocarbon dates Q-555 5228±120 Fallahogy, Co. Londonderry Q-653 5238±120 Fallahogy, Co. Londonderry Q-554 6810±140 Fallahogy, Co. Londonderry Y-95 7680±110 Toome Bay, Co. Londonderry References Deevey, E.S. (ed.), 1967. Radiocarbon Measurements: Comprehensive Index, 1950-1965. Radiocarbon 7:133- 211. Smith, A.G., 1961. Cannons Lough, Kilrea, Co. Derry: Stratigraphy and pollen analysis. Proceedings of Royal Irish Academy 61(B): 369-383. Smith, A.G., 1970. Late- and Post-glacial vegetational and climatic history of Ireland: A review. In: Stephens, N., Glasscock, R. (eds), Irish Geographical Studies. Queen's University of Belfast. pp 65-88. Coding ? -ca 11700 yr B.P. very high (4) ca 11700-10500 yr B.P. intermediate (2) ca 10500-10300 yr B.P. very high (4) ca 10300-9950 yr B.P. high (3) ca 9950-9000 yr B.P. low (1) ca 9000-0 yr B.P. infilling, not coded. Preliminary coding: 2/4/1993; Final coding: 21/7/1993 Coded by GY and SP Coolteen, Ireland Coolteen (52 21'N, 6 36'W, ca 50m above sea level) is a completely infilled sedimentary basin, and its surface now consists of a marsh covering ca 5ha. The catchment area is ca 50ha, most of which is the catchment of a channel now separated from the marsh by a man-made bank but which must formerly have entered it near the outflow (Craig, 1978). This small marshy depression lies on glacial tills, within the limit of the advance of Midlandian ice which is the extent of drift of the last glaciation (Colhoun and Mitchell, 1971). The basin probably originated as an ice-scour or erosion hollow in the general land surface. The stratigraphy of the deposits was reconstructed from a transect of ca 14 borings across the basin (Craig, 1978). There are four cores (69B, 71A, 71D and 71E) from the centre of the basin, taken less than 100m apart. The longest core (71A) is 9m long. The sedimentary sequence is the same in all four cores, although the thickness of individual layers varies between cores. The changes of water depth in the former lake between ca 12500 and 8500 yr B.P. are based on changes in lithology and aquatic assemblages. There are 8 radiocarbon dates (Craig, 1978; Dresser and McAulay, 1974). Three of these dates (I-5035, I-5036 and I-5037) are thought to be too old as a result of the introduction of old carbon into the system and its uptake by aquatic plants. These dates are not used for the chronology. The uppermost 1-1.5m of the sediment cores are not described. The lacustrine sediments are underlain by glacial tills. In core 71D (682-750cm) and core 71E (733-770cm) there are grey sands and clays, and pinkish clayey till. A radiocarbon sample from a depth of 725-735cm in core 71E is dated to 12470±155 yr B.P. (D-109). The basal lacustrine sediments are black detritus gyttja (470-579cm in core 69B, 893-900cm in core 71A, 650- 680cm in core 71D and 683-733cm in core 71E). The aquatic assemblage includes Potamogeton, Myriophyllum, Ranunculus, Elatine and Sparganium. The detrital nature of the sediments suggests that they were deposited in relatively shallow water between ca 12500 and 12000 yr B.P. The aquatic assemblage is consistent with this interpretation. The overlying sediment is grey calcareous banded clay (384-470cm in 69B, 766-843cm in 71A, 570-650cm in 71D and 595-683cm in 71E). The preservation of banding suggest that the lake was deep with anoxic bottom waters. The aquatics include Potamogeton, Myriophyllum, Ranunculus Elatine and Sparganium, but the abundance is less than the underlying layer, probably consistent with increased depth. This interval dates to ca 12000-11400 yr B.P. The overlying sediment is brown-black gyttja (250-384cm in 69B, 544-766cm in 71A, 366-570cm in 71D and 375-595cm in 71E), indicating a decrease in water level between ca 11400 yr B.P. and 10500 yr B.P. The aquatic assemblage is characterised by increase in Ranunculus and Elatine, consistent with decreased depth. The next unit is grey clay (127-250cm in 69B, 206-544cm in 71A, 168-366cm in 71D and 130-375cm in 71E). Sediment contains occasional organic and sandy bands, stones and Potamogeton leaves; organic bands are more frequent in the lower part of the unit. The clayey nature of the sediments and the preservation of banding suggest rather deep water. The sand and stone layers may reflect erosion intervals or short-lived episodes of lower water levels. The relative absence of aquatic pollen suggests that erosion is the most likely explanation. We therefore interpret this unit as indicating high water levels between 10500-10150 yr B.P. The overlying sediment consists of green-brown transitional gyttja (107-127cm in 69B, 181-206cm in 71A, 145-168cm in 71D and 100-130cm in 71E). The aquatic assemblage is characterised by a decrease in Potamogeton, Myriophyllum in 71A; and a slight increase in Ranunculus, Typha and Littorella in 69B. The change in lithology and aquatics suggest that the lake became shallower after 10150 yr B.P. The uppermost sediment is peat and peaty gyttja (97-107cm in 69B, 50-181cm in 71A and 110-145cm in 71D). The aquatic assemblage is characterised by decreased Potamogeton, Myriophyllum and Ranunculus. The changes in sediment and aquatics suggest that the lake became infilled between ca 9300 and 8500 yr B.P. There is no lacustrine sediment record after ca 8500 yr B.P. In the status coding: very low (1) is indicated by peat and peaty gyttja with very few aquatics, low (2) by detritus gyttja; intermediate (3) by gyttja with more aquatics; high (4) by clay with bands. Radiocarbon dates I-5035 10880±190 127-137cm, upper clay in 69B, ATO I-5036 11800±170 259-266cm, brown gyttja in 69B, ATO I-5037 11940±180 367-375cm, clay gyttja in 69B, ATO I-5038 12020±180 475-480cm, detritus gyttja in 69B I-5039 12390±160 555-560cm, detritus gyttja in 69B D-107 9055±95 140-150cm, peat in 71A D-108 10210±110 180-190cm, gyttja in 71A D-109 12470±155 725-735cm, detritus gyttja in 71E References Colhoun, E.A. and Mitchell, G.F., 1971. Interglacial marine formation and late glacial freshwater formation in Shortalstown, Co. Wexford. Proceedings of the Royal Irish Academy: 71B, 211-245. Craig, A.J., 1973. Studies on the Ecological history of South-east Ireland, Using pollen influx analysis and other methods. Unpublished Ph.D. thesis, University of Dublin. Craig, A.J., 1978. Pollen percentage and influx analysis in South-east Ireland: A contribution to the ecological history of the Late-glacial period, Journal of Ecology: 66, 297-324. Dresser, P.Q. and McAulay, I.R., 1974. Dublin radiocarbon dates II. Radiocarbon 16: 6-9. Coding ca 12500-12000 yr B.P. low(2) ca 12000-11400 yr B.P. high(4) ca 11400-10500 yr B.P. intermediate(3) ca 10500-10150 yr B.P. high(4) ca 10150-9300 yr B.P. intermediate(3) ca 9300-8500 yr B.P. very low(1) Preliminary coding: 28/4/1993; Final coding: 15/7/1993. Coded by SPH and GY Cregganmore, Ireland The site referred to here as Cregganmore (54 15'N, 9 36'W, 60m above sea level), is a small unnamed lake in Cregganmore townland, County Mayo (McKeever, 1984). The lake is approximately 260m in diameter and has a maximum depth of 1.5m. There is no surface inflow and the catchment area is confined to a zone a few hundred metres around the lake. There is an outflow stream, which joins a slightly larger stream draining from the surrounding blanket bog and drains to the sea, some 6km northwards. The site lies beyond but close to the ice limits of the last glacial maximum (McKeever, 1984). An 8m core, taken from the southwestern end of the lake in a water depth of 1.5m, provides a sedimentary record back to before 12,000 yr B.P. (McKeever, 1984). A short core of surface sediment was taken a few metres away from the main core. Note that depths in McKeever (1984) are given from the water surface, not from the sediment/water interface. Changes in relative water depth are reconstructed on the basis of changes in lithology and aquatic pollen and macrofossil assemblages. The chronology is based on 3 radiocarbon dates and pollen correlation with other radiocarbon-dated sites from Ireland (McKeever, 1984). The basal sediment (below 8.62m) consists of relatively inorganic material, with a variable component of sand, silt and clay. Somewhat more organic layers associated with bryophyte debris occur between ca 8.67-8.71m, 8.91-8.92m, 8.98-9.03m, 9.15, 9.23 and between 9.37-9.40m. The macrofossil assemblage is devoid of aquatic macrophytes. The terrestrial pollen from this unit was scarce and somewhat degraded. The overlying unit (7.80-8.62m) consists of relatively homogeneous dark organic sediments, with a moderately high sand content. The change in lithology is consistent with increased water depth. A diverse aquatic flora, including Ranunculus, Potamogeton and Myriophyllum, is represented in both the macrofossil and pollen assemblages, consistent with increased depth. The overlying unit (5.55-7.80m) consists of homogeneous, dark organic sediments with remains of aquatic plants. The lithology suggests an increase in water depth. Changes in the aquatic pollen and macrofossil assemblage may indicate changes in water depth. The interval between 7.50-7.80m is characterised by the absence of aquatic macrophytes. The interval between 6.60-7.50m is characterised by a diverse aquatic flora, including Ranunculus, Potamogeton and Myriophyllum. The interval between 6.50-6.60m is characterised by the disappearance of aquatic macrophytes. The interval between 6.10-6.45m is characterised by a dramatic increase in aquatic pollen abundance and a diverse aquatic flora, including Ranunculus, Potamogeton and Myriophyllum. The interval between 5.90-6.05m is characterised by the disappearance of aquatic macrophytes. The interval between 5.55-5.85m is characterised by a fairly sparse aquatic flora with Ranunculus and some Potamogeton. The overlying unit (5.00-5.55m) is a highly organic sandy silt. The uppermost part of the unit (5.00-5.30m) is highly fibrous. The change in lithology is consistent with shallowing. The absence of macrofossils in the basal part (5.40-5.55m) of the unit is consistent with shallowing. However, there is a big increase in aquatic pollen in the upper part of the unit above 5.30m, and Nymphaea and Potamogeton are represented in the macrofossil assemblages. The overlying unit (4.00-5.00m) consists of homogeneous, dark organic sediment with remains of aquatic plants, consistent with increased water depth. The pollen and macrofossil assemblages indicate a diverse aquatic flora, including abundant Nymphaea and Potamogeton. McKeever (1984) suggests that the shift from Nymphaea and Potamogeton to Isoetes and Sphagnum within this zone corresponds to a decrease in pH and argues that "changes in water level or progressive limnological developments are more likely explanations of these changes than climatic alterations" (p. 31). The overlying unit (3.50-4.00m) is highly fibrous. This change in texture may indicate shallowing. A decline in the abundance of Nymphaea and an increase in Myriophyllum may be consistent with shallowing. The sediments between 3.30-3.50m are devoid of aquatic macrofossils. This may mark the culmination of the shallowing trend. The overlying unit (2.78-3.30m) consists of homogeneous, dark organic sediment with remains of aquatic plants, consistent with an increase in water depth. The uppermost sediments (1.50-2.78m) are primarily inorganic silts, with occasional thin, more organic bands (e.g. 2.48-2.50m, 2.53-2.78m). The pollen and macrofossil records are characterised by a much less abundant representation of aquatics, a decline in the importance of Nymphaea and an increase in Isoetes. These changes may be consistent with shallowing. In the status coding, very low (1) is indicated by inorganic material, with bryophyte remains and scarce, degraded terrestrial pollen; low (2) by relatively inorganic deposits with a sparse, depauperate aquatic assemblage; intermediate (3) by sandy organic sediments, with a moderately diverse aquatic assemblage; and high (4) by organic sediments with abundant and diverse aquatics. Reference McKeever, M.H., 1984. Comparative Palynological Studies of Two Lake Sites in Western Ireland and North- Western Spain. M.Sc. thesis, Trinity College, Dublin, 63 pp. + appendices. Radiocarbon Dates Beta-9158 9830+160 6.32-6.42m Beta 9159 11900+170 7.65-7.75m Beta-6738 10820+100 8.30-8.40m, ATY ? Regional pollen dates 690-740cm Graminae zone, 10,900-12,000 yr B.P. 550-580cm Betula zone 9000-9500 yr B.P. 430-530cm Corylus increase, 9000-6500 yr B.P. 360cm 5000 yr B.P. Coding pre-13000 yr B.P. very low (1) 13740-11900 yr B.P. intermediate (3) 12100-9250 yr B.P. high (4) 9250-8250 yr B.P. intermediate (3) 8250-5850 yr B.P. high (4) 5850-4300 yr B.P. intermediate (3) 4300-3050 yr B.P. high (4) 3050-0 yr B.P. low (2) Preliminary coding: March 1989; Final coding: June 1989 Coded by: SPH Sheeauns, Ireland Lough Sheeauns (53 33'N, 10 3'W, 18m above sea level) is a small lake with the area of ca 1.1ha (120x90m) and a maximum depth of ca 5.5m. It lies in a long valley which runs east-west from Cleggan to the inner reach of Ballynakill Harbour. The lake is steep-sided and has little marginal aquatic vegetation. A small, artificial drainage channel enters from the western side. There is an artificial outflow to the east into Ballynakill Lough. The present lake is artificially low; comparison of the 1893 and 1898 editions of Ordnance Survey maps shows that the lake level and size decreased over this time, the lake measuring ca 190x116m (ca 2.2ha) in 1893 (Molloy and O'Connell, 1991). The catchment area is less than 50ha (Molloy and O'Connell, 1987). The underlying bedrock is schist (Tanner and Shackleton, 1979). The catchment soils are Brown Podzolics. There are three cores from the lake (Molloy and O'Connell, 1987, 1991): Core SHE I was from the centre of the lake (water depth of ca 5.5m) and covers the last ca 5000 yr B.P.; Core SHE III from nearby is ca 6m long and includes a short Late-glacial sequence at the base. The third core (SHE IV) was taken from southern side of the outflow channel (33m to the east of the lake edge). The sediment in SHE III and SHE I is uniform lake mud, and peat in SHE IV. Lake level changes are based on the changes of aquatic assemblages and organic content of sediment from SHE III and SHE I. The chronology is based on 13 radiocarbon dates from SHE III (Molloy and O'Connell, 1987, 1991). The basal sediment in SHE III (500-582cm, 10300-7530 yr B.P.) has an organic content of 45%. The aquatic assemblage includes quite high percentages of Potamogeton and Nymphaea (ca 45%) as well as some Myriophyllum. Deep water is indicated by the abundance of Potamogeton and Nymphaea and the absence of shallow water aquatics. The overlying lake mud in SHE III (444-500cm, 7530-5805 yr B.P.) is characterised by a decrease in Potamogeton and Nymphaea, and the appearance of Menyanthes, suggesting shallowing. The organic content of the sediment (60%) increases, consistent with somewhat shallow conditions. The aquatic assemblage between 396-444cm in SHE III is characterised by increasing Nymphaea, Typha, Alisma, Sphagnum and Menyanthes, and apparently decreasing Nuphar. The organic content reaches a maximum (70%). The change of aquatics and organics suggests the lake was lower between 5805 and 5455 yr B.P. Between 300-396cm in SHE III (5455-3150 yr B.P.), The aquatic assemblage is characterised by an increase in Nymphaea and Potamogeton, the disappearance of Typha and Alisma, and sparse Menyanthes. the organic content decreased to ca 60%. These changes suggest an increase in water depth. The overlying lake mud (228-300cm, 3150-1780 yr B.P.) contains moderate Nymphaea and Menyanthes, and Nuphar and Myriophyllum begin to increase sharply. The organic content is low (55%). The absence of Alisma and Typha, the decrease in Nymphaea and Menyanthes, and the increase in Nuphar and Myriophyllum suggest increasing water depth. The uppermost sediment in SHE III (200-228cm) contains mainly Menyanthes and abundant bog plants (Cyperaceae, Myrica). The record of uppermost lake mud comes from SHE I (10-40cm). The aquatic assemblage is characterised by an increase in Potamogeton and Nymphaea, and appearance of Epilobium, suggesting an intermediate water depth since ca 1700 years. In the status coding, low (1) is indicated by lake mud with high organic content, increase in Typha, Alisma and Menyanthes; intermediate (2) by lake mud with moderately high organic content, decrease in Potamogeton and Nymphaea, and appearance of Menyanthes; moderately high (3) by lake mud with relatively low organic content, increase in Nuphar and Myriophyllum; and high (4) by minimum organic content, abundant Potamogeton and Nymphaea, and the absence of shallow water aquatics. References Molloy, K and O'Connell, M., 1987. The nature of the vegetational changes at about 5000 B.P. with particular reference to the elm decline: Fresh evidence from Connemara, western Ireland. New Phytologist 106: 203-220. Molloy, K and O'Connell, M., 1991, Palaeoecological investigations towards the reconstruction of woodland and land-use history at Lough Sheeauns, Connemara, western Ireland. Review of Palaeobotany and Palynology 67: 75-113 Tanner, P.W.G. and Shackleton, R.M., 1979. Structure and stratigraphy of the Dalradian Rocks of the Beannabeola Area, Connemara, Eire. Special Publication of the Geological Society of London 8: 243- 256. Radiocarbon dates GrN-14500 2400±80 214-218cm lake mud core SHE III, ATO GrN-14499 1970±60 234-238cm lake mud core SHE III GrN-14498 2340±50 250-254cm lake mud core SHE III GrN-14503 2870±60 294-298cm lake mud core SHE III GrN-14502 3940±60 318-322cm lake mud core SHE III GrN-14497 4500±70 359-361cm lake mud core SHE III GrN-14501 4660±40 390-394cm lake mud core SHE III GrN-14042 4870±60 404-408cm lake mud core SHE III GrN-14041 4920±45 420-424cm lake mud core SHE III GrN-14040 5110±70 436-440cm lake mud core SHE III GrN-14039 5340±45 452-456cm lake mud core SHE III GrN-14496 6910±90 503-507cm lake mud core SHE III GrN-14495 9270±100 574-578cm lake mud core SHE III Coding 10,300-7530 yr B.P. high (4) 7530-5805 yr B.P. intermediate (2) 5805-5455 yr B.P. low (1) 5455-3150 yr B.P. intermediate (2) 3150-1780 yr B.P. moderately high (3) 1780-0 yr B.P. intermediate (2) Preliminary coding: 31/3/1993; Final coding: 27/7/1993. Coded by GY and SP Castiglione, Italy The Valle di Castiglione (41 53'30"N, 12 45'35"E, 44m above sea level) is an artificially-drained lake basin in an explosion crater on the northern flank of the Alban Hills volcanic complex (Alessio et al., 1986; Follieri et al., 1988). The lake was drained at the beginning of the 19th century (Narcisi et al., 1992). The crater is circular and has a diameter of about 1.3 km (Narcisi et al., 1992). Maximum rim elevations of ca 100m above sea level occur on the eastern side, while to the west the rim has been eroded and reaches an elevation of only 49m above sea level. The catchment area of the crater is ca 150ha. The crater is overlain by pyroclastic lava flows of the IV Tuscolano-Artemisio period and thus was formed sometime before 0.36 my (Radicati di Brozolo et al., 1978; Bernadi et al., 1982). A second lacustrine basin lies directly to the south of the Valle di Castiglione. This basin, which is known as the Pantano (or Marsh) Borghese, lies at elevations between 47-60m and is infilled by lacustrine and fluviolacustrine sediments. The Pantano Borghese is drained by a small stream, the F.so dell'Osa. which drains into the Aniene River. According to Narcissi et al. (1992) the Pantano Borghese basin could have been connected to the Valle di Castiglione at times of high water level by means of a channel through the lowest point in the southwestern rim of the crater. The catchment area of the combined basins would have been ca 6000ha. The presence of numerous springs in the Pantano Borghese basin, and the occurrence of diffuse water emissions in the Valle di Castiglione, indicate that groundwater inflow may play an important role in the hydrology of these basins (Narcisi et al., 1992). An 88.25m wire-line drill core (S1) from the centre of the basin provides a sedimentary record back to ca 250,000 yr B.P. (Follieri et al., 1988). A second 15.63m-long wire-line drill core (S2) was taken about 15m from S1 in an attempt to cover some gaps in the original core record (Alessio et al., 1986; Follieri et al., 1988). One or two 4m-long Hiller cores were also taken (Alessio et al., 1986; Follieri et al., 1988). A multidisciplinary study of the uppermost 10m of sediment, including lithology, geochemistry, mollusc and other faunal assemblages, and pollen stratigraphy has been carried out (Alessio et al., 1986). The stratigraphy of the whole sequence is described by Narcisi et al. (1992) and the pollen stratigraphy by Follieri et al. (1986, 1988) and Magri (1989). Twenty-one radiocarbon dates were made on samples between 1.15-55.20m (Alessio et al., 1986). The oldest radiocarbon age of 41,700+4700 yr B.P. was obtained from a sample from between 15.40-15.60m (R-1554); the remaining eight dates from below 15m depth proved to be infinite. Two of the dates in the upper part of the core show dating reversals (R-1549 and R-1318). The remaining ten dates appear to be acceptable, although Alessio et al. (1986) stress the possibility of contamination by 14C-depleted allochthonous organic matter and/or volcanic sediments. Budassi and Mortari (1986), in a geotechnical investigation which indicated an erosion surface at ca 35m depth, suggested that the sediments overlying this unconformity were younger than 25,000 yr B.P. This conflicts with the radiocarbon-based reconstruction, and can be assumed to be erroneous. The sedimentation rate of the uppermost radiocarbon-dated 10m averages 0.31 mm/yr (Alessio et al., 1986; Magri, 1989). Magri (1989) argues that the long-term average sedimentation for the whole core is about 0.32 mm/yr. This assertion is based on the sedimentation rates calculated for a sequence of annual laminations at around 70m in the core, and the good correlation with the oxygen isotope curve of Martinson et al. (1987) and the precessional cycle of insolation as described by Berger (1978). It is highly unlikely, given the variable lithology, that the actual sedimentation rate was constant. Indeed, the presence of a "chernozem"-type palaeosol between 24-25m (Follieri et al., 1988; Narcissi et al., 1992) indicates a fairly long hiatus in sedimentation. However, Magri (1989) suggests that 0.32 mm/yr can be regarded as close to the real value and thus can be used, in the absence of alternative dating methods, for dating the lower part of the core. This assertion is accepted by other authors (e.g. Narcissi et al., 1992). In any case, there is no alternative given the lack of any other kind of dating on the lower part of the core. However, the chronology of the uppermost 10m of the core can readily be fixed by linear interpolation between radiocarbon dates and this method is used here to establish the chronology of changes in water depth over the last 30,000 years, in preferance to assuming a constant sedimentation rate as was done in the reconstructed vegetation history (Follieri et al., 1986, 1988; Magri, 1989). Narcissi et al. (1992) have interpretated the sedimentary sequence, in particular changes in the geochemistry of the sediments, from the Valle de Castiglione in terms of changing humidity. However, they do not reconstruct changes in lake level or water depth consistently. The changes in water depth documented here are reconstructed from changes in sediment lithology, aquatic pollen preservation, the occurrence of lacustrine molluscs, and aquatic pollen assemblages. The basal unit (ca 74-88.25m) is calcareous-tuffaceous silts, containing several discrete tephra layers. The aquatic flora consists of occasional Myriophyllum and Alisma. Botryococcus is present in moderate abundance, and Pediastrum is recorded occasionally. This unit can be dated to ca 230,000-270,000 yr B.P. The overlying unit (ca 69-74m) consists of thinly laminated silts. The preservation of laminations suggests that water depth increased. The aquatic assemblage is rather similar to the underlying unit, except that Cyperaceae occur and Pediastrum is absent. This unit is dated to between ca 210,000-230,000 yr B.P. Shallower conditions after ca 210,000 yr B.P. are indicated by a return to calcareous-tuffaceous silt deposition between ca 62.5-69m. The aquatic assemblage of zone VdC4 (62.80-69.00m: ca 195,000-210,000 yr B.P.) is characterised by moderately high and variable values of Botryococcus, low but continuous representation of Myriophyllum, and occasional Pediastrum, Alisma, Sparganium, Typha and Cyperaceae. This assemblage is consistent with relatively shallow conditions. The sediments between ca 60-62m are laminated silts, indicating a return to deeper water conditions. In the basal part of the unit (60.38-62.80m, zone VdC5 : ca 190,000-195,000 yr B.P.) the aquatic assemblage is characterised by moderate Botryococcus and Myriophyllum, with occasional Pediastrum, Alisma, Sparganium, Typha, Nymphaceae and Cyperaceae. The increased abundance of Myriophyllum and the presence of Nymphaceae is consistent with increased water depth. The overlying sediments (ca 54-60m) are calcareous-tuffaceous silts. The disappearance of laminations is consistent with shallowing. The disappearance of Nymphaceae from the aquatic assemblage between 58.40- 60.38m (zone VdC6) is consistent with shallowing, as is the presence of mollusc shells. This interval is dated to between 170,000 and 190,000 yr B.P. The overlying sediments (53.5-54m) are tuffaceous organic silts grading into tuffaceous carbonaceous silts (52- 53.5m). The occurrence of tuffaceous silts probably reflects volcanic activity, and has no significance in terms of changes in water depth. This is confirmed by the fact that the aquatic assemblage is similar to that of the underlying unit, characterised by high abundances of Botryococcus with increasing abundance of Pediastrum and Alisma, a decline in Myriophyllum, and occasional Nymphaceae and Cyperaceae. Molluscs continue to be common through this unit. The overlying unit (44-52m) consists of calcareous-tuffaceous silts. The abundance of molluscs is consistent with a pronounced shallowing. Follieri et al. (1988, p.338) suggest that the very high abundances of Chenopodiaceae in the lower part of this zone (50.38-52.40m) is possibly influenced "by a local situation of high lacustrine salinity". Chenopods are also quite abundant near the top of the unit The upper part of the zone has extremely low pollen concentrations, suggesting that the sediments have been subjected to oxidisation. The presence of carbonate concretions in the top 0.5m of the unit is also consistent with pronounced shallowing. This shallow interval is dated to between 135,000 and 165,000 yr B.P. This shallowing trend seems to have continued after ca 135,000 yr B.P. The overlying unit (ca 32-44m) consists of tuffaceous-carbonaceous silts. The presence of bioturbation structures indicate shallow conditions. The lower part of this zone (42.85-47.80m) is almost devoid of pollen. Between 37.35-41.44m (ca 115,000-125,000 yr B.P.) the aquatic assemblage is characterised by moderate Botryococcus, with occasional Myriophyllum, Alisma, Typha and Cyperaceae, consistent with shallow conditions. Indeterminate pollen reaches its maximum concentration, consistent with oxidation of pollen. Aquatics are not recorded in zone VdC11 (35.38-37.35m: ca 110,000-115,000 yr B.P.) and pollen concentrations in general are low, suggesting that the sediments have been subjected to oxidation. Somewhat deeper conditions after ca 110,000 yr B.P. (ca 32.00-35.38m) are indicated by an increase in pollen concentration and the occurrence of an aquatic assemblage characterised by moderate Botryococcus, with occasional Pediastrum, Myriophyllum, Alisma, Sparganium and Nymphaceae. The overlying sediments consist of carbonaceous-tuffaceous silts or tuffaceous-carbonaceous silts (28-32m). Changes in the aquatic assemblages may reflect changes in water depth, but in general the water depth seems to have been similar to the underlying unit. Botryococcus increases between 30.40-32.00m (ca 95,000-100,000 yr B.P.) and becomes very abundant; Myriophyllum also increases in abundance, while Alisma and Typha occur occasionally. The aquatic assemblage of zone VdC13 (28.00-30.40m: 85,000-95,000 yr B.P.) is characterised by occasional Botryococcus and Myriophyllum. The overlying unit (26-28m) is a tuffaceous silt. The occurrence of bioturbation structures suggests the lake became shallower. Botryococcus becomes more abundant, while Myriophyllum declines in abundance, consistent with shallowing. This interval is dated between 80,000 and 85,000 yr B.P. The overlying unit (24-26m) is a calcareous-tuffaceous silt. Molluscs occur but are not common, suggesting moderate water depth. The absence of bioturbation structures is consistent with an increase in water depth. The development of a "chernozem" type palaeosol in the upper part of this unit indicates a major hiatus in sedimentation (Narcissi et al., 1992). The overlying unit (22-24m) consists of tuffaceous sands, indicating shallow conditions. The unit is extremely poor in pollen, consistent with the lithology and very shallow conditions. The overlying sediments are tuffaceous silts, and are still characterised by poor pollen preservation, suggesting the persistence of relatively shallow conditions. The overlying unit consists of calcareous-tuffaceous silts. The aquatic assemblage of the lower part of zone VdC16 (14.00-20.50m: ca 45,000-62,000 yr B.P.) is characterised by abundant Botryococcus, moderate Pediastrum and Myriophyllum, and occasional Alisma, Sparganium and Typha. Between 10.60-14.00m (ca 33,000-45,000 yr B.P.), Botryococcus is only moderately abundant, as is Pediastrum, while Myriophyllum, Alisma and Sparganium occur occasionally. The better pollen preservation and the more diverse aquatic assemblage are consistent with increased water depth after ca 62,000 yr B.P. The sediments between 7.80-10.60m are medium to fine-grained, slightly calcareous, lacustrine muds. Well- preserved lacustrine mollusc shells occur locally. The overlying unit (5.30-7.80m) consists of massive fine-grained tuffites. Lacustrine mollusc shell fragments occur between 7.00-7.70m. Alessio et al. (1986) suggest that the texture of these volcanic deposits and the presence of lacustrine molluscs indicates that they were laid down under water. Burrow casts are present in the uppermost part of the unit, suggesting that the water became shallower. Two samples from near the base of this unit are radiocarbon dated to 25800±600 and 24900±370 yr B.P., and a sample spanning the transition to the overlying unit is dated to 20300±700 yr B.P. respectively. The overlying sediments (4.15-5.30m) are calcareous lacustrine muds, characterised by the presence of abundant mollusc shells and frequent bioturbation structures. The nature of the sediments and the presence of bioturbation structures suggests that the water depth was comparatively shallow. This interval is dated to between 20,300 and ca 12,985 yr B.P. There is a thin layer of dark tuffite between 4.00-4.15m. The unit contains rare terrestrial mollusc shell fragments. Alessio et al. (1986) suggest that the unit was laid down in water. The absence of bioturbation structures and the comparative paucity of molluscs suggests that the water may have been deeper than formerly. However, these differences may also reflect the rather tough nature of turbidite sediment. The overlying sediments (3.03-4.00m) are calcareous muds, containing occasional mollusc fragments. A sample from near the top of this unit was radiocarbon-dated to 9200±200 yr B.P., suggesting the unit was deposited between ca 12,270 and 7970 yr B.P. The deposition of peaty muds between 1.10-3.03m indicates shallowing. The upper part of the unit contains abundant freshwater and terrestrial mollusc shells. The presence of (inwashed) terrestrial molluscs and the general abundance of freshwater molluscs is consistent with shallowing. A sample from near the top of this unit has been radiocarbon dated to 3480+50 yr B.P. Of the three dates from the middle of the unit, two are stratigraphically consistent but a third yielded an anomalously old age of 7130±75 yr B.P. This suggests that there may have been some reworking of older material exposed around the margin of the lake when the water level fell. This interval of lowered water level culminated with the deposition of peat between 0.90-1.10m. This shallow interval is dated to between 2570 and 3150 yr B.P. An increase in water depth after ca 2570 yr B.P. is marked by the deposition of fine-grained muds between 0.70- 0.90m. The presence of bioturbation structures indicates that the water was quite shallow. A return to very shallow conditions after ca 2000 yr B.P. is indicated by peat deposition between 0.23-0.70m. The presence of thin calcareous mud interbeds near the base of the unit suggests fluctuating water depths initially. Thin calcareous mud interbeds also occur near the top of the unit. The uppermost sediments (0.00-0.23m) are calcareous muds, indicating an increase in water depth in the last ca 660 years. In the status coding, an hiatus (0) is shown by palaeosol development; very low (1) is indicated by intervals with poor pollen preservation or abundant chenopods, or by sandy sediments; low (2) by peat deposition; Intermediate (3) by peaty or organic mud deposition; moderately high (4) by calcareous muds or tuffites with bioturbation structures or abundant mollusc shells; high (5) by calcareous muds or tuffites without bioturbation structure and with sparse molluscs or only fragments of mollusc shells; very high (6) by laminated sediments. References Alessio, M., Allegri, L., Bella, F., Calderoni, G., Cortesi, C., Dai Pra, G., De Rita, D., Esu, D., Follieri, M., Improta, S., Magri, D., Narcisi, B., Petrone, V. and Sadori, L., 1986. 14C dating, geochemical features, faunistic and pollen analyses of the uppermost 10m core from Valle di Castiglione (Rome, Italy). Geologica Romana 25: 287-308. Bernardi, A., De Rita, D., Funiciello, R., Innocenti, F. and Villa, I.M., 1982. Chronology and structural evolution of Alban Hills volcanic complex, Latium, Italy. Abstract, Workshop on Explosive Volcanism, S. Martino al Cimino, C.N.R., Roma and N.S.F., USA. Follieri, M., Magri, D. and Sadori, L., 1986. Late Pleistocene Zelkova extinction in central Italy. New Phytologist 103: 269-273. Follieri, M., Magri, D. and Sadori, L., 1988. 250,000-year pollen record from Valle di Castiglione (Roma). Pollen et Spores 30: 329-356. Magri, D., 1989. Interpreting long-term exponential growth of plant populations in a 250 000-year pollen record from Valle di Castiglione (Roma). New Phytologist 112: 123-128. Narcisi, B., Anselmi, B., Catalano, F., Dai Pra, G. and magri, G., 1992. Lithostratigraphy of the 250,000-year lacustrine sediments core from Valle di Castiglione crater (Roma). Quaternary Science Reviews 11: 353-362. Radicati di Brozolo, F., Huneke, J.C. and Wasserburger, G.J., 1978. Ar/Ar and Rb-Sr age determinations on Quaternary volcanic rocks from the Roman volcanic province. 4th International Conference on Geochronology and Cosmochronology, Denver, pp 445-448. Radiocarbon Dates R-1314 3480±50 1.15-1.25m peat mud, core S1 R-1319 4490±65 2.09-2.19m peat mud, core S2 R-1320 5280±65 2.19-2.25m peat mud, core S2 R-1318 7130±75 1.90-2.00m peat mud, core S2, ATO? R-1321 9200±200 3.31-3.40m calcareous mud, core S2 R-1331 14200±145 4.30-4.50m calcareous mud, core S2 R-1332 20300±270 5.13-5.50m calcareous mud, core S2 R-1547 24900±370 7.17-7.30m clay silt, core S2 R-1548 25800±600 7.30-7.50m clay silt, core S2 R-1550 27200±1500 10.00-10.10m calcareous mud, core S1 R-1549 31300±900 9.85-10.00m calcareous mud, core S1 R-1551 32900±1600 10.10-10.25m calcareous mud, core S1 R-1552 >34000 15.10-15.20m calcareous mud, core S1 R-1316 >38000 41.60-41.70m clay silt, core S1 R-1315 >40000 19.20-19.30m calcareous mud, core S1 R-1317 >40000 55.08-55.20m calcareous mud, core S1 R-1554 41000±4700 15.40-15.60m calcareous mud, core S1 R-1553 >43000 15.20-15.40m calcareous mud, core S1 R-1555 >43000 17.00-17.10m clay silt, core S1 R-1556 >43000 17.10-17.20m clay silt, core S1 R-1557 >43000 17.20-17.40m clay silt, core S1 Coding 230-270k high (5) 210-230ka very high (6) 195-210ka high (5) 190-195ka very high (6) 165-190ka moderately high (4) 135-165ka very low (1) 110-135ka moderately high (4) 85-110ka high (5) 80-85ka moderately high (4) ca 80ka hiatus 62-80ka very low (1) 30-62ka high (5) 30000-21000 yr B.P. high (5) 12985-22000 yr B.P. moderately high (4) 7970-12985 yr B.P. high (5) 3150-7970 yr B.P. intermediate (3) 2570-3150 yr B.P. low (2) 2000-2570 yr B.P. moderately high (4) 660-2000 yr B.P. low (2) 0-660 yr B.P. high (5) Preliminary coding: 7th September 1990; Final coding: January 1993. Coded by: SPH Fucino, Italy Lake Fucino was a perennial lake lying in the tectonic basin of d'Avezzano (also known as the Piana de Fucino: 42 N, 13.55 E, 667m above sea level) in central Italy (Raffy, 1970; Giraudi, 1989). The lake has been subject to extensive human interference since the time of the Emperor Claudius, and was finally drained in 1875/6 (Raffy, 1970). The resulting plain lies at an altitude of 649-667m above sea level. Prior to its drainage, Lake Fucino had an area of ca 15000ha and a maximum depth of 18m (Giraudi, 1989). There does not appear to have been a surface outflow from the lake. The lake was clearly subject to rather large natural variations in level: the maximum depth was 21m in 1816 and only 9.4m in 1835 (Raffy, 1970). The catchment area, excluding the area of the lake, was ca 71000ha. The catchment is relatively mountainous; individual peaks reach elevations well above 2000m (e.g. Mt. Velino 2487m, Mt. Sirente 2349m). These mountains were glaciated at the last glacial maximum (Raffy, 1970). Much of the underlying bedrock is limestone. The presence of karst springs on the Fucino Plain suggests that groundwater inputs must have played a fairly important role in the hydrological balance of the lake. Karstic drainage, via swallow holes, may have played a role in controlling the maximum elevation of the lake. There are swallow holes, known to be active in historic times, located along the southwestern edge of the Plain. Giraudi (1989) argues that the importance of karstic drainage, influenced as it is by vegetation cover and glacial processes, is a function of climatic variations. Thus the record of water-level changes in this basin can be considered as a reasonable indicator of past changes in the water balance. Lacustrine deposits dated to the penultimate glaciation occur at elevations between ca 780-800 m on the eastern side of the basin (Raffy, 1980). A long core (> 68m) from the centre of the basin provides a pollen record going back to the last interglacial (Follieri et al., 1986). Unfortunately, only a summary diagram has been published and there are no radiometric dates on the core. Late Quaternary lacustrine terraces occur around the lake, up to an elevation of 720m above sea level (Giraudi, 1989). The region is tectonically active and subject to surface faulting, and this has resulted in some displacement of the shoreline terraces. Nevertheless, changes in lake level since ca 30,000 yr B.P. have been reconstructed on the basis of archaeological, geomorphological and historical evidence (Giraudi, 1989). The chronology is based on 5 radiocarbon dates, 2 dated tephras and archaeological dating (Giraudi, 1989; Ferrara et al., 1961). The oldest lake deposits are sandy gravels and gravels of deltaic origin. These sediments contain water- transported artefacts of Mousterian age (>35,000 yr B.P.) and are covered by a tephra layer, known as the Campanian Ignimbrite and dated to ca 33,000 yr B.P. (Capaldi et al., 1985). Thus, these deltaic sediments provide evidence of a high lake level (710m+) before ca 33,000 yr B.P. Radmilli (1963, 1977) has identified waterlain sediments in caves (e.g. Grotta La Punta and Ortucchio Cave) lying at elevations between 695-710m. The caves were subsequently occupied by prehistoric hunters sometime after ca 18,000 yr B.P. This suggests that the waterlain deposits can be correlated with the high lake levels before ca 33,000 yr B.P. indicated by deltaic sedimentation. Charcoal from the overlying cave occupation layer has been radiocarbon dated to 14,488±800 yr B.P. (Ferrara et al., 1961). A 10cm bed of volcanic ash overlies the cave occupation sites (Radmilli, 1963). The caves were apparently abandoned for some time, but subsequently reoccupied during the interval between 13,000 and 10,500 yr B.P., suggesting that the lake remained lower than 695m. The decrease in lake level after ca 18,000 yr B.P. is registered by two shoreline features. The Pescina shoreline terrace occurs at an elevation between 685-725m and overlies lacustrine sediments dated between 33,000 and 18,000 yr B.P. According to Giraudi (1989) this terrace documents the lake level between ca 18,000-20,000 yr B.P. and the exposure of the terrace occurred when lake level fell sometime after 18,000 yr B.P. The Avezzano terrace is a wave-cut feature occurring between 695-715m. It is cut into both limestone outcrops and deltaic deposits, and thus is younger than ca 33,000 yr B.P. The similarity in elevation suggests that it formed at the same time as the Pescina shoreline, and thus documents the lake level between ca 18,000-20,000 yr B.P. Outwash fans associated with late-Pleistocene glacial moraines, cut into the Pescina shoreline. The fans are thus younger than 18,000 yr B.P. The fan surface is covered locally by a tephra thought to correspond to the Neapolitan Yellow Tuff, which is dated to ca 13,000 yr B.P. (Di Girolamo et al., 1984). The distal ends of these fans occurs at an elevation between 670-675m. The lake must have been below this level when the fans were formed. A rock pediment (Pescina-San Benedetto), formed by running water, is cut into the deltaic deposits, and the Pescina and Avezzano shorelines. The distal part of this pediment is at an elevation of 668-680m. This pediment is thought to have been formed sometime between 18,000 and 7,500 yr B.P. The Mesolithic village of Ortucchio, which lies at an altitude of 658m a.s.l., indicates that the lake was below this elevation by ca 10,500 yr B.P. The Ortuccio site appears to have been continuously occupied until after the lower Neolithic (7500-6500 yr B.P.). The village was then abandoned in response to flooding consequent on an increase in lake level (Irti, 1980). The San Benedetto-Venere wave cut terrace (665-675m) is cut into the Pescina-San Benedetto rock pediment. It is thought to have been formed during this middle Neolithic rise in lake level (Giraudi, 1989). The village of Ortucchio was reoccupied during the Eneolithic period (4200-3800 yr B.P.), indicating that the lake had fallen below 658m by this time. During the Protovillanoviano culture (3100-2800 yr B.P.), the settlement extended down to an elevation of 655m (Irti, 1980). This suggests that the lake level continued to fall. However, Ortucchio was finally abandoned at the end of the Protovillanoviano period, probably in response to a rise in lake level and flooding (Irti, 1980). The lowermost shore terrace is the Luco terrace (662-663m). The terrace is formed from silty clays with layers of sand and gravel. Similar deposits are found at the archaeological site of Ruscella, overlying a tomb dated to 2960+100 yr B.P. The Luco shore terrace is thus associated with the increase in lake level that occurred after the Protovillanoviano period (2800-2300 yr B.P.). Lacustrine bars are found along the edge of the historic lake depression. At one location, bar sediments cover a black soil containing Bronze Age artefacts, dated to 3600-3800 yr B.P. This soil overlies older bar deposits, occurring at 667-668m, and probably related to the level of the lake in Neolithic times. Younger bars, containing artefacts from Roman, mediaeval and historic times, occur in the elevation range 672-673m and 668m. Historical records indicate that the lake was at 660m in 150 A.D., just prior to the Roman drainage works were implemented (D'Amato, 1980). This artificial outflow probably only remained active until the 5-6th century A.D. During the 16th and first part of the 17th centuries A.D. the lake was at fairly low levels. Between 1750 A.D. and 1875 A.D. the lake level fluctuated between 655 and 672m, with minimum levels in 1750 A.D. and maximum levels in 1816 A.D. In the status coding, very low (1) is indicated by lake levels below 655m; low (2) by lake levels between 655- 660m; intermediate (3) by lake levels between 660-670m; high (4) by lake levels between 670 and 685m; very high (5) by lake levels above 685m. References Capaldi, G., Civetta, L. and Gillot, P.Y., 1985. Geochronology of Plio-Pleistocene volcanic rocks from southern Italy. Rendiconti della Societa Italiano Mineralogica è Petrologiga 40: 25-44. D'Amato, S., 1980. Il Primo Prosciugamento del Fucino. Centro Studi Marsicani, Avezzano, 292pp. Di Girolamo, F., Ghiara, M.R., Lirer, L., Munno, R., Rolandi, G. and Stanzione, D., 1984. Vulcanologia e petrologia dei Campi Flegrei. Bollettino della Societa Geologica Italiana 103: 349-413. Ferrara, G., Fornaca-Rinaldi, G. and Tongiorgi, E., 1961. Carbon-14 Dating in Pisa - II. Radiocarbon 3: 99- 104. Follieri, M., Magri, D. and Sadori, L., 1986. Late Pleistocene Zelkova extinction in Central Italy. New Phytologist 103: 269-273. Giraudi, C., 1989. Lake levels and climate for the last 30,000 years in the Fucino area (Abruzzo-Central Italy) - a review. Palaeogeography, Palaeoclimatology, Palaeoecology 70: 249-260. Irti, U., 1980. La presenza dell'uomo. In: Cianciusi, V., Irti, U. and Grossi, G. (Eds), Profili di Archeologia Marsicana. Rotary Club, Avezzano, 185pp. Radmilli, A.M., 1963. Il paleolitico superiore nel riparo maurizio. Contributo per una datazione del detrito di falda nel Fucino. Atti della Societa Toscana di Scienze Naturali in Pisa. Memorie Ser. A 70: 220-243. Radmilli, A.M., 1977. Storia dell'Abruzzo dalle origini all'Età del Bronzo. Giardini, Pisa, 455pp. Raffy, J., 1970. Etude géomorphologique du bassin d'Avezzano (Italie Centrale). Méditeranée 1: 3-18. Radiocarbon Dates n/a 2960±100 material from tomb, Ruscella (date from Giraudi, 1989) Pi-80 3366±130 charcoal, Ortucchio archaeological site, settlement layer overlying Eneolithic village Pi-153 10581±100 charcoal, from younger occupation layer, Grotta La Punta 1. Pi-23 12619±410 younger occupation layer, Ortucchio Cave. Pi-152 14488±800 charcoal, in lower occupation layer, associated with volcanic ash, Grotta La Punta 2 Tephra Dates 13000 yr B.P. Neapolitan Yellow Tuff 33000 yr B.P. Campanian Ignimbrite Coding ca 35,000-33,000 yr B.P. very high (5) ca 20,000-18,000 yr B.P. very high (5) ca 18,000-10,600 yr B.P. intermediate (3) ca 10,500- 6,500 yr B.P. low (2) ca 6,500- 4,200 yr B.P. low (2) ca 3,100- 2,800 yr B.P very low (1) ca 2,800- 1,800 yr B.P. intermediate (3) ca 450- 200 yr B.P. low (2) ca 200- 150 yr B.P. intermediate (3) ca 150- 125 yr B.P. high (4) ca 125- 75 yr B.P. intermediate (3) "modern" intermediate (3) Preliminary coding: August 1990; Final coding: September 1992 Coded by: SPH Lago di Ganna, Italy Lago di Ganna, Italy (45.87 N, 8.83 W, 452m above sea level) lies in the Valganna valley, north of Varese in the central Southern Alps (Schneider and Tobolski, 1985; Drescher-Schneider, 1987). The lake is chiefly fed by the Margorabbia Brook, which rises in a mire in the south of the valley. There are a few smaller streams that drain from the surrounding mountains into the lake. The lake overflows via a small stream into the Lago di Ghirla, which in turn overflows via the Tresa River into Lago Maggiore. The Valganna valley is surrounded by mountains reaching altitudes of 800-1100m above sea level. The catchment bedrock consists mainly of siliceous rocks, including gneiss, porphyry and porphyrite. The valley was occupied by a glacier during the last glacial maximum. Moraines associated with the retreat of this glacier occur to the south and north of the lake, but do not appear to have been responsible for the formation of the lake. The lake bottom sediments provide a record back to ca 17,000 yr B.P. (Drescher-Schneider, 1987). The bottom stratigraphy has been reconstructed from 14 cores along one longitudinal (L1) and two transverse (Q1 and Q2) transects (Schneider and Tobolski, 1983, 1985). The reconstruction here, which is based on changes in lithology, aquatic pollen and plant macrofossils (Schneider and Tobolski, 1983, 1985), broadly follows that described in Schneider and Tobolski (1983) and Drescher-Schneider (1987). There are no radiocarbon dates from Lago di Ganna. The chronology is provided by pollen correlation with nearby radiocarbon dated sites (Schneider and Tobolski, 1985). Although there are some local differences, the cores all show the same basic stratigraphy. The basal sediments are sand and clay, derived from local erosion. The overlying unit is a strongly laminated silt. The preservation of laminations suggests a deepwater phase. The overlying unit is a silty detritus gyttja. Parts of this unit are laminated. The increase in organic content and the fact that the laminations are not continuous suggests water depth decreased. The overlying unit is a detritus gyttja, containing diatoms and abundant plant macrofossils. The increase in organic content, and the presence of plant macrofossils, is consistent with deposition in relatively shallow water and indicates further shallowing. The overlying unit is coarse detritus gyttja, consistent with furthering shallowing. The uppermost sediments are peat. Peat formation began ca 3500 yr B.P. in the nearshore core Q2-20, but only by ca 2500-2200 yr B.P. in more central cores. A more detailed record of changes in water depth is provide by the aquatic macrofossil assemblages, in particular variations in the relative abundance of Charales and in floating-leaved aquatics (Schneider and Tobolski, 1985). The lake was relatively shallow until ca 14,500 yr B.P. Deeper conditions were registered between 14,500 and ca 8800 yr B.P. This interval can be correlated with the interval of strongly laminated sediment deposition. The Holocene is characterised by six relatively shallow phases, marked by abundant Charales and an increase in Phragmites and sedge-community macrofossils. These shallow phases occurred ca 7200-8800 yr B.P., ca 5800- 6200 yr B.P., ca 2900-5300 yr B.P., ca 1900-2400 yr B.P., ca 600-1300 yr B.P. and during the last 200 years. These phases are separated by intervals of deeper water, marked by a decrease in Charales and an increase in floating-leaved aquatics such as Nymphaea, Potamogeton and Myriophyllum. In the status coding, low (1) is indicated by an aquatic assemblage with abundant Charales; intermediate (2) by an aquatic assemblage with abundant floating-leaved aquatics; and high (3) by laminated sediments. References Drescher-Schneider, R., 1987. Type-region central Southern Alps CH-e. Lundqua Report 27: 195-197. Schneider, R. and Tobolski, K., 1983. Palynologische und stratigraphische Untersuchungen im Lago di Ganna (Vares, Italien). Botanica Helvetica 93: 115-122. Schneider, R. and Tobolski, K., 1985. Lago di Ganna - Late-glacial and Holocene environments of a lake in the Southern Alps. Dissertationes Botanicae 87: 229-271. Coding 17000-14500 yr B.P. low (1) 14500- 8800 yr B.P. high (3) 8800- 7200 yr B.P. low (1) 7200- 6200 yr B.P. intermediate (2) 6200- 5800 yr B.P. low (1) 5800- 5300 yr B.P. intermediate (2) 5300- 2900 yr B.P. low (1) 2900- 2400 yr B.P. intermediate (2) 2400- 1900 yr B.P. low (1) 1900- 1300 yr B.P. intermediate (2) 1300- 600 yr B.P. low (1) 600- 200 yr B.P. intermediate (2) 200- 0 yr B.P low (1) Preliminary coding: March 1988; Final coding: April 1988 Coded by: SPH Ellasjøen, Norway Ellasjøen (74 23'N, 19 3'E, 20.8m above sea level) is the deepest lake in the southern part of Bjørnøya Island, Norway. The basin is situated in a deep valley between Oswaldfjellet (162m above sea level) and Alfredfjellet (420m above sea level). The lake area is ca 110ha and the maximum depth is over 40m. There is a outlet stream and the distance to the coast is approximately a kilometre. The bedrock in the catchment is Palaeozoic sandstone and limestone (Hyvärinen, 1968). There are three cores taken from the lake (Hyvärinen, 1968). A 5m-long core, taken in a water depth of 26-27m, consists of uniform dark mud. A 0.5m-long core, consisting of sandy and gravelly sediment, was taken from a water depth of 20m. A 2.25m-long core (core B1) from a water depth of 22m provides a lithological, pollen and diatom record back to ca 9400 yr B.P. Changes in water depth are reconstructed on the basis of changes in lithology, diatom and aquatic pollen assemblages. The chronology is based on pollen correlation with nearby radiocarbon-dated sites (Hyvärinen, 1968, 1970; Olsson, 1968): Skinkevatna (core B12), ca 13km to the north; Trullvatnet (core S7) in Nordaustlandet and Strøen (core S28) in Spitsbergen, ca 30-50 km from Ellasjøen. The basal sediment from core B1 (below 225cm) is coarse mineral deposit. There is reddish clayey silt with angular pebbles between 205-225cm. The deposits probably represented fluvial input during the late glacial (Hyvärinen, 1970). The overlying sediment (190-205cm) is brown grey silty mud, suggesting shallow water. Diatom assemblage (sample 4 at ca 200cm of the core) is dominated by benthic diatoms, such as Amphora ovalis f., Achnanthes flexella, Campylodiscus spp., and Pinnularia viridis, consistent with shallow conditions. The presence of Equisetum and Sphagnum in abundance is consistent with this interpretation. This unit is placed on the lower part of pollen zone IIa, when pollen zone IIa is from 200-150cm of core B1 (Hyvärinen, 1968) and is dated to ca 9-5ka yr B.P. (from Hyvärinen, 1970). This suggests the unit was formed ca 9400-8200 yr B.P. The overlying sediment (190-20cm) is dark sulphide mud with banded sections. This change in lithology could reflect deeper water, and the onset of anoxic conditions within the basin. Hyvärinen (1968) argues that the basin is quite shallow, so that it is unlikely that sulphide mud deposition was due to a phase of meromixis. He suggests that the lake has a low oxidation capacity because it is ice-covered most of the year, and that episode of sulphide mud deposition may therefore reflect a period of greater-than-present organic input which could not be oxidised during the ice-free period. This explanation seems unlikely because loss-on-ignition is lower during the interval of sulphide deposition than in the over- or underlying units. Furthermore, the interval during which the lake was ice-covered is likely to have been shorter during the mid-Holocene, which implies that the opportunity for sediment oxidation would have been greater (consistent with the loss-on-ignition data) rather than less or similar to today (as implied by Hyvärinen's argument). We interpret the banded sulphide-rich deposits a indicating deep water after ca 8200 yr B.P. Biological variations recorded in sulphide mud allow this unit to be subdivided. The diatom assemblage from sample 5 at ca 170cm is characterised by benthic species, such as Pinnularia spp. (20%) and Amphora ovalis f. (6%), suggesting moderately deep water. There are marked decline in Equisetum and Sphagnum between ca 180 and 140cm, consistent with this interpretation. The diatom assemblage from sample 6 at ca 150cm is characterised by abundant Melosira islandica spp. helvtica (16%) and presence of Tabellaria fenestrata, Coscinodiscus lacustris and Cyclotella comta (species <5%). This planktonic assemblage suggests deep water. The absence of Equisetum between ca 140-105cm in the aquatic pollen assemblage supports this hypothesis. The diatom assemblage between ca 130cm to 20cm (samples of 7, 8, 9 and 10) is characterised by the disappearance of planktonic species, abundance of benthic species, such as Campylodiscus spp. (24% at 104cm, 20% at 125cm and 10% at 80cm) and presence of Pinnularia microstauron and Nitzschia palea, suggesting decreased water depth. The reappearance of Equisetum above ca 105cm is consistent with this interpretation. The boundaries between the three subunits are dated to ca 5800 yr B.P.(160cm) and 4200 yr B.P. (130cm), based on pollen zones of IIc, IIb, IIa and the lower part of III which are correlated to ca 9000 yr B.P. (200cm), 5000 yr B.P. (150cm), 3000 yr B.P. (100cm) and 2000 yr B.P. (75cm) respectively (from Hyvärinen, 1968; 1970). The uppermost sediment (0-20cm) is silty mud. The coarser lithology suggests shallow water. The diatom assemblage is dominated by benthic species (Campylodiscus spp., 76%) but epiphytic species are present (Fragilaria pinnata, 6%), consistent with shallow water. The unit is dated to the last ca 530 yr B.P. In the status coding, low (1) is indicated by silty mud with benthic diatoms dominant or abundant Equisetum; intermediate (2) by sulphide mud with a benthic diatom assemblage; high (3) by sulphide mud with planktonic diatoms dominant, and absence of Equisetum. Radiocarbon dates U-2301 11,200±500 pollen zone I, core B12, Skinkevatna. U-2064 8900+1200-1000 pollen zone I, core B12, Skinkevatna. U-2042 8300+1400-1200 pollen zone I, core B12, Skinkevatna. St-2534 11135±130 pollen zone I, core S28, Strøen. St-2454 10255±875 pollen zone I, core S28, Strøen. St-2776 6485±100 pollen zone IIa, core S7, Trullvatnet. St-2453 7240±200 pollen zone IIa, core S7, Trullvatnet. St-2665 5550±140 pollen zone IIa, core S7, Trullvatnet. St-2666 4745±120 pollen zone IIb, core S7, Trullvatnet. U-2050 4600+1200-1000 pollen zone IIb, core B12, Skinkevatna. Hel-40 2010±130 pollen zone II/III, core S7, Trullvatnet. References Hyvärinen, H., 1968. Late-Quaternary sediment cores from lakes on Bjørnøya. Geografiska Annaler 50 (A): 235-247. Hyvärinen, H., 1970. Flandrian pollen diagrams from Svalbard. Geografiska Annaler 52 (A): 213-222. Olsson, I. U., 1968. Radiocarbon analyses of lake sediment samples from Bjørnøya. Geografiska Annaler 50 (A): 246-247. Coding ca 9400-8200 yr B.P. low (1) ca 8200-5800 yr B.P. intermediate (2) ca 5800-4200 yr B.P. high (3) ca 4200-530 yr B.P. intermediate (2) ca 530-0 yr B.P. low (1) Preliminary coding: 12/12/1993; Final coding: 25/2/1994 Coded by GY and SP Endletvatn, Norway Endletvatn (69 44'N, 19 5'E, 35m above sea level) is a shallow lake in the northern part of Andøya Island, Northern Norway. The lake is ca 25ha in area, with large marginal topogenic mires at its southwest end. A small brook enters the southwestern part of the lake. There is an outlet southeastwards to the sea. The distance from Endletvatn to the sea is ca 2km. The bedrock in the catchment is Precambrian gneiss, mostly covered by till and glaciofluvial sediments (Vorren, 1978). The lake has lacustrine sediments after it was deglaciated ca 18,000 yr B.P. (Vorren, 1978). The stratigraphy of the lake deposits has been reconstructed from four cores at two sites (a, b) in the mire to the west of the lake. This area was part of the open lake until the mid-Holocene (Vorren, 1978). A 8.2m-long core (core 1970-a) and a 10m-long core (core 1972-a) were taken from site a, ca 50m from the southwest end of the mire at 36m above sea level. A ca 11.25m-long core (core 1970-b) and a 10.8m-long core (core 1974-b) were taken from site b, ca 100m northeast of site a. Both core sites are ca 500m from the shore of the lake. The record for the last 5000 years has not been studied. Changes in water depth are reconstructed from changes in lithology, lamination structures, aquatic pollen assemblages, moss macrofossils (Vorren, 1978), and diatom assemblages (Foged, 1978). There are 14 radiocarbon dates from cores 1970, 1972 and 1974 respectively. One date is rejected owing to contamination and two dates have reversed ages inconsistent with the local pollen chronology (Vorren, 1978). The chronology is therefore based on 11 radiocarbon dates. The basal unit is till (below ca 10.0m in core 1972, below ca 10.7m in core 1974), dated to pre 18,000 yr B.P. A sample from this unit in core 1974 is dated to 19,100±270 yr B.P. (T-1775b, 10.10-10.28m). The lacustrine sediment begins with minerogenic silt with intraformational conglomerate detritus and a faintly laminated structure (10.0-9.0m in core 1972, 10.7-9.8m in core 1974). A sample in core 1974 from this unit yields an age of 18,100±800 yr B.P. (T-1775a, 9.98-10.08m). The overlying sediment is laminated clay (9.0-8.4m in core 1972, 9.8-8.5m in core 1974 and below 8.1m in core 1970). The fine lithology and distinctly laminated structure suggest increased water depth. The quite low sedimentation rate (0.03 cm/yr) is consistent with deep water. A sample (9.05-9.15m in core 1974) from this unit yields radiocarbon dates of 14,990±130 yr B.P. (T-2152a) and 15,300±290 yr B.P. (T-2152b). This unit is dated to ca 15,100-14,300 yr B.P. The overlying sediment is massive to faintly-laminated coarse silt (below 7.45m in cores 1970, 7.4-8.4m in 1972 and 7.5-8.5m in core 1974). The coarser sediment and disappearance of laminations is consistent with shallowing. In core 1974, an increase in sedimentation rate from 0.03 cm/yr to 0.08 cm/yr (9.1-7.4m) is consistent with decreased water depth. Two samples from the top of this unit are radiocarbon-dated to 12,920±110 yr B.P. (T-1887, 7.30-7.45m, core 1974) and 12,710±200 yr B.P. (T-963, 7.42-7.52m, core 1970) respectively. This unit is dated to ca 14,300-12,700 yr B.P. The overlying unit is organic silty or clayey gyttja (7.45m-4.0m in cores 1970, 7.4-6.0m in 1972 and 7.5-5.0m in 1974), suggesting a general increase in water depth. In core 1974, planktonic Stephanodiscus hantzschii in diatom assemblage is common in the initial part of this unit (7.23-7.31m), suggesting a shift to deep water conditions. In core 1972, a decrease in sedimentation rate from 0.15 cm/yr to 0.02 cm/yr is consistent with increased water depth. There are four radiocarbon-datings between 12,610±220 yr B.P. and 10,510±510 yr B.P. concentrated during the late glacial. The upper boundary of this unit belongs to the middle of the Atlantic period based on pollen correlation (Vorren, 1978). Changes in aquatic pollen assemblages from core 1970 and moss macrofossils from core 1974 allow this unit to be subdivided. Between 5.7-7.4m in core 1970, there are moss layers. Abundant moss macrofossils, such as Aulacomnium turgidum, Drepanocladus spp. are also present in core 1974, suggesting relatively shallow water. Two samples from the top of this unit are radiocarbon-dated to 10,510±510 yr B.P. (T-1888, 5.45-5.55m) and 10,850±280 yr B.P. (T-1889, 5.75-5.85m) respectively. Between 4.6-5.7m in core 1970, the aquatic assemblage is characterised by increases in Myriophyllum, Sparganium and Potamogeton, suggesting increased water depth. A marked decrease in moss layers in cores 1972 and 1974 (5.5-5.0m) is consistent with increased water depth. Planktonic Melosira arenaria occurs in the diatom assemblage (5.1-5.38m, core 1974), consistent with deep water conditions. This subunit belongs to pollen zones of YDc-BO (5.8-4.6m, ca 10,500-7000 yr B.P.), and is dated to ca 10,400-7000 yr B.P. Between 4.6-4.0m in core 1970, the aquatic assemblage is characterised by abundant Myriophyllum (5.3%) and an increase in Equisetum, suggesting slightly decreased water depth. The diatom assemblage is characterised by benthic species. The occurrence of moss layers is consistent with shallowing. This subunit belongs to pollen zone AT (4.6-3.1m, after ca 7000 yr B.P.). The uppermost sediments from the lake margins are telmatic sediments (above 4.0m in cores 1970-a and 1972- a, and above 5.0m in cores 1970-b and 1974-b). The Carex-Sphagnum peat deposits reflect marginal infilling. This unit covers pollen zones from the middle AL to SA, after ca 5000 yr B.P. The record for the last 5000 years has not been studied, but the lake has water area of 25ha today. We assume the lake has an intermediate water depth to present. In the coding status, low (1) is indicated by silt with high minerogenic content or coarse silt; moderately low (2) by organic silty or clayey gyttja with moss layers; intermediate (3) by organic silty or clayey gyttja with abundant Myriophyllum; moderately high (4) by organic silty or clayey gyttja with Myriophyllum, Potamogeton and Sparganium, and with planktonic diatoms; high (5) by clay with laminations. Peat deposit around the lake margins after ca 5000 yr B.P. reflects infilling, and is not coded. Radiocarbon dates T-1888 10,510±510 545-555cm, silty/clayey gyttja, core 1974 T-1889 10,850±280 575-585cm, silty/clayey gyttja, core 1974 T-1510 10,940±270 625-630cm, silty/clayey gyttja with moss, core 1972 T-1576 11,800±2000 742-752cm, sandy clay, core 1972, ATY T-1511 12,610±220 665-667cm, silty/clayey gyttja with moss, core 1972 T-963 12,710±200 742-752cm, coarse silt, core 1970 T-1887 12,920±110 730-745cm, coarse silt, core 1974 T-1575 14,800±1800 975 T-1573 9900±1600 820-840cm, silt, core 1972 ATY -995cm, laminated clay, core 1972 T-2152a 14,990±130 905-915cm, laminated clay, core 1974 T-2152b 15,300±290 905-915cm, laminated clay, core 1974 T-1775a 18,100±800 975-995cm, coarse silt, core 1974 T-1512 18,710±400 998-1008cm, laminated clay, core 1972 EJECTED T-1775b 19,100±270 1010-1028cm, coarse silt, core 1974 References Foged, N., 1978. Diatoms from the Middle and Late Weichselian and the Early Flandrian period on Andøya, north Norway. Boreas 7: 41-47. Vorren, K.-D., 1978. Late and Middle Weichselian stratigraphy of Andøya, north Norway. Boreas 7: 19-38. Vorren, T., Vorren, K.-D., Alm, T., Gulliksen, S. and Løvlie, R., 1988. The last deglaciation (20,000 to 11,000 B.P.) on Andøya, northern Norway. Boreas 17: 41-77. Coding ca 18,300-15,100 yr B.P. low (1) ca 15,100-14,300 yr B.P. high (5) ca 14,300-12,700 yr B.P. low (1) ca 12,700-10,400 yr B.P. moderately low (2) ca 10,400-7000 yr B.P. moderately high (4) ca 7000-5000 yr B.P. intermediate (3) ca 5000-0 yr B.P. intermediate (3) Preliminary coding: 27/4/1994; Final coding: 16/5/1994. Coded by GY and SPH Lerstadvatn, Norway Lerstadvatn (62.5 N, 6.5 E, 44m above sea level) is a small lake in the Ålesund area on the west coastal region of Norway. It lies in the coastal strandflat area. The Lerstadvatn basin consists of two sub-basins: the one at the western end is now occupied by a peat bog; the other is still open water. The lake has an area of 5ha and a maximum water depth of 5.45m (Kristiansen et al., 1988). There is an outlet northwards to the sea; the distance from Lerstadvatn to the sea is ca 1km. The catchment bedrock is gneiss with carbonate (Gjelsvik, 1951) and the surface is covered with Quaternary tills. The catchment area is ca 25ha. The Ålesund area was deglaciated after ca 12,500-12,300 yr B.P. (Kristiansen et al., 1988); Lerstadvatn lies near the marine limit for the area (Reite, 1967) but was isolated from the sea ca 12,400 yr B.P. (Lie et al., 1983). The stratigraphy of the lake deposits has been reconstructed from 27 cores from the basin (Kristiansen et al., 1988). Two ca 7m-long cores (cores 502-30-01 and 502-30-02a) from the bog in the western basin, and a ca 10m-long core (core 502-30-03) taken from the lake in a water depth of 2.50m, provide a sedimentary record back to before 12,650 yr B.P. (Kristiansen et al., 1988). The basal sediments (Formation A) are marine sediments. The record for the last 8900 years has not been studied. Although the authors do not reconstruct changes in water depth, they do state that the changes in sediment composition are primarily a reflection of climate changes (Kristiansen et al., 1988). Changes in water depth for 12,400-8900 yr B.P. are reconstructed from changes in lithology, aquatic pollen and algal assemblages, and sedimentation rate. The chronology is based on eleven radiocarbon dates from lacustrine units (Kristiansen et al., 1988). The basal sediments in cores 502-30-01 and 02a (7.18-6.35m, Formation A) are silt and clayey silt. The formation is interpreted as of glaciomarine or cold marine origin and older than 12,400 yr B.P. (Lie et al., 1983; Kristiansen et al., 1988) The overlying sediment (6.35-5.653m, the Åse Member) is silty gyttja, with loss on ignition 10-60% and organic carbon 5-15%. The presence of aquatic pollen and planktonic algae marks the onset of lacustrine conditions after 12,400 yr B.P. Variations in organic content, plant remains, aquatic pollen and algal assemblages allow this unit to be subdivided. The lowermost part of this unit (6.35-6.14m) has a high silt and low organic content (ca 10%). The absence of plant remains suggests moderately deep water. The aquatic pollen is characterised by Potamogeton in abundance, consistent with deep conditions. Pediastrum and Botryococcus reach their highest abundance in this subunit, also consistent with deep water. This subunit is dated to ca 12,400-12,000 yr B.P. (Kristiansen et al., 1988). The overlying subunit (6.14-6.06m, the top part of Åse-1) is darker in colour and is characterised by an increase in organic content (up to 20%), suggesting decreased water depth. Plant remains, such as a leaf of Salix herbacea, occur in this subunit, consistent with shallowing. In the aquatic pollen assemblage, Sparganium type is present and Potamogeton decreases, consistent with shallowing. This subunit is dated to ca 12,000-11,800 yr B.P. (Kristiansen et al., 1988). The overlying subunit (6.06-5.85m, Åse-2) is highly organic (30-60%), suggesting a shallow water deposit. There are abundant plant remains, and decreased Potamogeton and increased Sparganium pollen, consistent with decreased water depth. Pediastrum is still abundant but Botryococcus decreased, consistent with decreased water depth. This subunit is dated to ca 11,800-11,300 yr B.P. A decrease in organic content (< ca 5%) and the absence of plant remains between 5.85-5.735m (Åse-3), suggests increased water depth ca 11,300-11,000 yr B.P. The aquatic pollen is characterised by Potamogeton and Nymphaea, consistent with increased depth. The presence of Pediastrum and increase in Botryococcus are consistent with this interpretation. Between 5.735-5.65m (Åse-4) the organic content increases (ca 40%) and there are lots of plant remains, suggesting a decrease in water depth. A decrease in Botryococcus and Pediastrum is consistent with decreased water depth. This subunit is dated to ca 11,000-11,050 yr B.P. The overlying sediment (5.65-553.5m, the Leirstad Member) is diatomite-silt with low organic content (2-3%) and low influx of minerogenic particles, suggesting moderately deep water. Aquatic pollen is abundant and the assemblage is characterised by Potamogeton and Myriophyllum, consistent with increased water depth. The algal assemblage is marked by a large increase in Pediastrum, consistent with increased depth. However, the abundance of Botryococcus remains low. The sedimentation rate decreases from the Åse (ca 0.52 mm/yr) to the Leirstad (ca 0.11 mm/yr), supporting increased water depth. A layer (2-3cm thick) of volcanic ash (identified as the Vedde Ash) occurs within this unit. It is considered to be inwashed from the catchment rather than in situ (Mangerud, pers. comm., 1992). Vedde Ash Bed is radiocarbon-dated to 10,680±80 yr B.P. (Mangerud et al., 1984), so this suggests that the Leirstad Member was formed sometime around 10,680 yr B.P. A sample at the top of the unit is dated to 10,340±110 yr B.P. (T-4585). The uppermost unit (the Hatlen Formation) is nearly 7m thick and covers the entire Holocene (Mangerud, pers. comm., 1992). The lowermost part of the Hatlen Formation (9.5-9.10m below water surface in core 502-30-03) is a light brown gyttja with finely dispersed plant remains, suggesting decreased water depth. The aquatic pollen is characterised by a decrease in Potamogeton and Myriophyllum, and the presence of Isoetes and Menyanthes, consistent with shallowing. The algal assemblage is marked by a decline in Pediastrum abundance, consistent with decreased water depth. An increase in sedimentation rate from the Leirstad to the Hatlen (0.3 mm/yr) is consistent with decreased water depth. A sample from the top of this unit is radiocarbon-dated to 9010±100 yr B.P. (T-3987A). The middle part of the Hatlen Formation is darker brown gyttja with increased dy content, and the upper 1.5m is a very loose dy. The lithology probably indicates a continuation of relatively deep water. Unfortunately the biotic assemblage has not been studied. Mangerud (1992) states that the modern lakes in this area of west Norway are always full due to their high rainfall of 2000 mm/yr, which implies the present lake-level is high and supports the lithological evidence of deep water. In the status coding, low (1) is indicated by silt gyttja with high organic content (30-70%), abundant plant remains, and low abundances of Pediastrum and Botryococcus; intermediate (2) by silt gyttja with moderately organic content (20%), plant remains and Sparganium type pollen; moderately high (3) by silt gyttja with low organic content (10%) or gyttja/dy, no plant remains, and abundant Potamogeton, Myriophyllum, Pediastrum and Botryococcus; high (4) by diatomite-silt with very low organic content (2-3%), abundant deep-water aquatic pollen and algae, and low sedimentation rate. Radiocarbon dates T-3987A 9010±100 ca 9.10m below water surface, Hatlen Formation, core 502-30-06 T-4586A 9400±100 ca 9.22m below water surface, Hatlen Formation, core 502-30-03 T-4161B 10330±290 ca 5.73m, Åse-4, core 502-30-01 T-4585A 10340±110 ca 9.47m below water surface, Hatlen Formation, core 502-30-03 T-4381 10680±80 ca 9.60m below water surface, inwashed material from Vedde Ash Bed, core 502-30-03 T-4161A 10860±140 ca 5.73m, Åse-4, core 502-30-01 T-3955A 11130±150 ca 5.66m, Åse-4, core 502-30-01 T-4158A 11640±170 ca 5.85m, Åse-2, core 502-30-01 T-4159A 11570±110 ca 5.95m, Åse-2, core 502-30-01 T-4160A 12050±110 ca 6.13m, Åse-1, core 502-30-01 T-3957A 12650±230 ca 6.32m, Åse-1, core 502-30-01 Note: The depths of samples are not given in Kristiansen et al. (1988) but approximate depths have assessed from Figures 7 and 17 (Kristiansen et al., 1988). References Gjelsvik, 1951. Oversikt over bergartene i SunnmØre og tilgrensede deler av Nordfjord. Norges Geologiska Undersokelse 179: 45 pp. Kristiansen, I.L., Mangerud, J. and LØmo, L., 1988. Late Weichselian/early Holocene pollen- and lithostratigraphy in lakes in the Ålesund area, western Norway. Review of Palaeobotany and Palynology 53: 185-231. Lie, S.E., Stabell, B. and Mangerud, J., 1983. Diatom stratigraphy related to Late Weichselian sea-level changes in SunnmØre, western Norway. Norges Geologiska Undersokelse 280:203-219. Mangerud, J., Lie, S.E., Furnes, H., Kristiansen, I.L. and LØmo, L., 1984. A Younger Dryas ash bed in Western Norway, and its possible correlations with tephra in cores from the Norwegian Sea and North Atlantic. Quaternary Research 21: 85-104. Mangerud, J., 1992. personal communication. Letter. Reite, A.J., 1967. Lokalglaciasjon på SunnmØre. Norges Geologiska Undersokelse 247: 262-287. Coding ca 12400-12000 yr B.P. moderately high (3) ca 12000-11800 yr B.P. intermediate (2) ca 11800-11300 yr B.P. low (1) ca 11300-11000 yr B.P. moderately high (3) ca 11000-11050 yr B.P. low (1) ca 11050-10200 yr B.P. high (4) ca 10200-8900 yr B.P. moderately high (3) ca 8900-0 yr B.P. moderately high (3) Preliminary coding: 18/9/1994; Final coding: 15/11/1994 Coded by GY and SPH Nedre Æråsvatn, Norway Nedre Æråsvatn (69 45'N, 19 4'E, 35m above sea level) is a shallow lake in the northern part of Andøya Island, Northern Norway. The lake area is ca 25ha and the water depth is ca 1.5m. A small brook enters the southern part of the lake from øvre Æråsvatn. There is an outlet northwards to Lake Storevatn and thence to the sea. The distance from Nedre Æråsvatn to the sea is ca 4km. The catchment bedrock is Precambrian gneiss, mostly covered by till and glaciofluvial sediments (Vorren, 1978). The lake has a continuous lacustrine sedimentary sequence after it was isolated from the sea, ca 15,500 yr B.P. (Vorren et al., 1988; Alm, 1993). The stratigraphy of the lake deposits has been reconstructed from eight cores from the lake (Vorren et al., 1988). A 10.55m-long composite stratigraphy, based on eight cores (cores A, B, C, E, F, G, J and L) from four holes drilled in an area of 2.5x1.5m in a water depth of 1.5m through the thickest sediments in the basin, provides a sedimentary record back to ca 21,000 yr B.P. (Vorren et al., 1988). The basal sediments (below 6.6m, units I, II and III) are glacial or marine. The record for the last 10,000 years (above ca 4.9m) has not been studied. in water depth for 15,500-10,000 yr B.P. (units IV, V and VI) are reconstructed from changes in lithology, lamination structures, aquatic pollen and algal assemblages. There are sixteen radiocarbon datings, but only six of these are on the lacustrine sediments (Vorren et al., 1988). Two of the dates yield anomalous ages. Thus the chronology is based on four radiocarbon dates from lacustrine units and reference datings from underlying marine units. The basal sediments (10.55-6.6m, Units I to III) are heavily folded, faulted and fractured silty, clayey sediment (unit I), sandy silt and algal silt (unit II and III). Vorren et al. (1988) suggest these deposits represent glaciolacustrine (before ca 20,000 yr B.P.) and marine environments (19,500-19,000 yr B.P. and 18,500-15,500 yr B.P.) based on the lithology, diatom and macroalgae assemblages. The overlying sediment (6.6-6.3m, the lower part of unit IV) is gelatinous organic silt with laminations, marking the onset of lacustrine conditions after 15,500 yr B.P. The presence of laminations suggests the water was moderately deep. The low loss-on-ignition (10-25%) is consistent with this interpretation. Pediastrum boryanum occurs in modest numbers, consistent with moderately deep water. Some Equisetum is present in this unit. This unit is dated to ca 15,500-13,700 yr B.P. (Vorren et al., 1988). Layers of silt and fine sand occur at irregular intervals through the gelatinous organic silt (unit IV, 6.6-6.0m), but are mainly concentrated between ca 6.3-6.25m (6.20-6.25cm in core B, 6.25-6.30m in core J and 6.27- 6.33m in core A). These layers are characterised by very low loss-on-ignition values (<10%) and very low density (<1.0). Vorren et al. (1988) suggest that the sand stringers may be caused by storms, and silt layers by littoral erosion or lake level fluctuations, implying very shallow water conditions or possible hiatuses. A sample from this unit (6.22-6.27m, core A) is radiocarbon-dated to 13,300±320 yr B.P. (T-5050A). We interpret these silt and sand layers as indicating a period of shallow conditions ca 13,700-13,300 yr B.P. The overlying sediment (6.2-6.0m, the upper part of unit IV) is gelatinous organic silt. The change in lithology suggests a slight increase in water depth. An increase in Pediastrum boryanum is consistent with increased water depth. The absence of laminations and increased loss-on-ignition (up to 40%) place a limit on the degree of deepening. Aquatic pollen is scarce. A sample from the unit top (5.95-6.00m, core J) yields radiocarbon dates of 12,750±230 yr B.P. (T-5582A) and 12,760±150 yr B.P. (T-5582B). This unit is dated to ca 13,000-12,800 yr B.P. The overlying sediment (6.0-5.45m, the lower part of unit V) is organic silt. The unit is indistinctly laminated, suggesting moderately deep water. More aquatic pollen is present in this unit, and the assemblage is characterised by Nymphaea, Sphagnum and Isoetes, consistent with intermediate water depth. The algal assemblage is characterised by abundant Pediastrum boryanum (6.2-5.8m), consistent with increased water depth. A relatively low loss-on-ignition (20-25%) is also consistent with this interpretation. This unit is date to ca 12,800-11,800 yr B.P. The overlying sediment (5.45-5.26m, the upper part of unit V) is organic silt with laminations. The presence of distinct lamination structures suggests increased water depth. The aquatic assemblage is characterised by Myriophyllum spicatum and M. alterniflorum, consistent with deep water. A sharp increase in Scenedesmus and the abundance of Pediastrum boryanum are consistent with increased water depth. This unit is dated to ca 11,800-11,400 yr B.P. There is a thin moss layer in organic silt unit in 5.26-5.10m, indicating quite shallow water, ca 11,400-11,000 yr B.P. The uppermost sediment (5.10-4.97m, unit VI) is silty organic sediment, suggesting increased water depth. The green algae assemblage is characterised by abundant planktonic species, such as Pediastrum, Tetraedron, Scenedesmus and Botryococcus, consistent with deep water. A lower minerogenic/organic ratio suggests deep water. A sample from this unit is radiocarbon-dated to 11,010±270 yr B.P. (T-5173A, 5.02-5.07m, core J). The unit is dated to ca 11,000-10,000 yr B.P. In the status coding, very low (1) is indicated by silt with sand stringers; low (2) by gelatinous organic silt, or by moss layer; intermediate (3) by organic/gelatinous organic silt with indistinct laminations, and with planktonic algae (Pediastrum) and aquatic pollen (Nymphaea and Isoetes); high (4) by silt with laminations, deep water aquatic pollen (Myriophyllum spicatum and M. alterniflorum), and abundant planktonic algae (Pediastrum boryanum and Scenedesmus), or by silty organic sediment with planktonic algae assemblage and low minerogenic matter. Radiocarbon dates T-5173A 11,010±270 5.02-5.07m, organic silt, core J T-5050B 12,120±110 6.22-6.27m, gelatinous organic silt, core A ATY. T-5582A 12,750±230 5.95-6.00m, organic silt, core J T-5582B 12,760±150 5.95-6.00m, organic silt, core J T-5172A 12,910±240 5.42-5.47m, organic silt, core J, REJECTED. T-5050A 13,300±320 6.22-6.27m, gelatinous organic silt, core A T-5579 14,240±750 6.61-6.64m, macro-algae, core B T-4792B 14,890±520 6.83-6.86m, algal silt, core A T-4792A 16,020±460 6.83-6.86m, algal silt, core A T-5580 16,150±330 6.69-6.73m, macroalgae, core B T-5581 17,800±230 7.26-7.27m, macro-algae, core B T-4791A 17,910±820 7.90-7.95m, algal silt, core E T-5278B 18,950±1090 7.90-7.95m, algal silt, core E T-4791B 18,950±280 7.90-7.95m, algal silt, core E T-4793A 19,100±670 10.30-10.33m algal silt, core G T-4793B 20,780±540 10.30-10.33m algal silt, core G Note: Sub-samples with different pretreatments are indicated by A (dilute NaOH) and B (dilute HCL to remove carbonates). References Alm, T., 1993. øvre Æråsvatn - palynostratigraphy of a 22,000 to 10,000 BP lacustrine record on Andøya, northern Norway. Boreas 22: 171-188. Vorren, K.-D., 1978. Late and middle Weichselian stratigraphy of Andøya, north Norway. Boreas 7: 19-38. Vorren, T., Vorren, K.-D., Alm, T., Gulliksen, S. and Løvlie, R., 1988. The last deglaciation (20,000 to 11,000 B.P.) on Andøya, northern Norway. Boreas 17: 41-77. Coding ca 15,500-13,700 yr B.P. intermediate (3) ca 13,700-13,300 yr B.P. very low (1) ca 13,300-12,800 yr B.P. low (2) ca 12,800-11,800 yr B.P. intermediate (3) ca 11,800-11,400 yr B.P. high (4) ca 11,400-11,000 yr B.P. low (2) ca 11,000-10,000 yr B.P. high (4) Preliminary coding: 23/4/1994; Final coding: 10/5/1994 Coded by GY and SPH øvre Æråsvatn, Norway øvre Æråsvatn (69 44'N, 19 3'E, 44m above sea level) is a shallow lake in the northern part of Andøya Island, Northern Norway. The basin occupies a sheltered valley, protected by mountains to the west, south and southeast. The lake area is 25ha (700x650m) and the maximum depth is ca 6m (Alm, 1993). Two small brooks enter the western part of the lake. There is an outlet northeastwards to Lake Nedre Æråsvatn and thence to Storvatn. The catchment area is 350ha. The bedrock in the catchment is Precambrian gneiss (Alm, 1993). The lake has a continuous lacustrine sedimentary record since ca 22,000 yr B.P. (Alm, 1993). The regional glacial advance in ca 19,000-18,000 yr B.P. covered nearby Lake Nedre Æråsvatn and Lake Endletvatn, but did not reach this basin (Alm, 1993). The marine limit in ca 18,000-15,500 yr B.P. occupied nearby Lake Nedre Æråsvatn, but did not influence Lake øvre Æråsvatn (K. Vorren, 1978; T. Vorren et al., 1988; Alm, 1993). The stratigraphy of the lake deposits has been reconstructed from ten cores along a single east-west transect across the lake (Alm, 1993). The investigated sediments form a submerged delta from the mouth of one of the inflow streams. Sediment thickness on the eastern side of the transect and near the outflow is very limited. A 14.10m-long composite stratigraphy, based on six cores (cores B, C, E, J, K and L) provides lithological, pollen and algal records back to ca 22,000 yr B.P. The record for the last 10,000 years has not been studied. Alm (1993) has outlined changes in lake level. Changes in water depth are reconstructed from changes in lithology, lamination structures, algal assemblages, the state of microfossil preservation and sedimentation rates, and generally follow those described by Alm (1993). The chronology is based on 21 radiocarbon dates from 19 samples within the interval 22,000-10,000 yr B.P. The basal sediment (14.10-13.84m, unit A) is slightly organic silt with dropstones and numerous thin, blue-grey laminae, grading into a minerogenic gyttja with numerous moss remains. The low organics and discontinuous laminations suggest moderately deep but unproductive conditions. The abundance of planktonic green algae (Pediastrum boryanum) is consistent with moderately deep water. A sample from this unit in core K (13.875- 13.94m) is radiocarbon-dated to 21,800±410 yr B.P. (T-8029A) and 21,520±150 yr B.P. (T-8029B). This unit is dated to ca 22,000-21,000 yr B.P. The overlying sediment (13.84-13.34m, unit B) is brown silty gyttja with laminated structures, suggesting increased water depth. A relatively low loss-on-ignition (10-30%) and low sedimentation rate (0.03 cm/yr) are consistent with deep water. The unit contains abundant Pediastrum boryanum, in a good state of preservation, supporting increased water depth. The sediments have a grainy or ped-like structure. Alm (1993) suggests this unit was formed under permafrost conditions with modest surface runoff during the spring/summer thaw. Three samples from this unit in core K are radiocarbon-dated to 17,740±270 (T-85600A, 13.37-13.395m), 18,820±200 (T-8559A, 13.57-13.62m) and 19,650±180 (T-8558A, 13.675-13.725) respectively. This unit is dated to ca 21,000-18,300 yr B.P. The overlying sediment (10.78-13.34cm, unit C) is gyttja. The lowermost 54cm (13.34-12.78m) is distinctly laminated. The laminations are less pronounced between 12.80-11.80m and again between 11.52-10.78m. The gyttja between 11.80-11.52m is unlaminated. The sediments are characterised by a low minerogenic and high organic content. Alm (1993) argues that the high organic content results from a relative concentration of nutrients under shallow conditions, and the low mineral content is due to limited surface runoff under the conditions of permanently frozen soils. He assumes the lake level was probably lowered more than 6m below the present level. Pediastrum declines markedly, consistent with shallowing. An increase in sedimentation rate from 0.03 cm/yr to 0.2 cm/yr could also support shallowing. The presence of laminated structures through most of the unit places a limit on the degree of shallowing (Alm, 1993). The change from distinctly laminated through indistinctly laminated to non-laminated gyttja suggests progressive shallowing, culminating in shallowest conditions between 16,800-16,100 yr B.P. This progressive shallowing is reflected in a gradual increase in the organic content, a decrease in the abundance of Pediastrum, and a deterioration in the preservation of algae in the sediments. Pediastrum is absent in the non-laminated gyttja. A return to somewhat deeper conditions after 16,100 yr B.P. is marked by the deposition of indistinctly laminated gyttja (11.52-10.78m). An increase in Pediastrum boryanum, and the presence of Scenedesmus, is consistent with increased water depth. The overlying sediment is silty gyttja (10.78-10.30m). The coarse lithology and disappearance of laminations suggest decreased water depth. The high organic content (70%) and poor preservation of Pediastrum are consistent with shallowing. This unit is dated to ca 15,100-12,800 yr B.P. A thin sandy-silty stringer occurs at 10.31-10.30m. Alm (1993) argues that this stringer indicates an hiatus in sedimentation. The incomplete nature of the Bølling-Alleröd pollen record, compared with nearby basins, is consistent with this hypothesis. The very low sedimentation rate (less than 0.01 cm/yr) between 10.305-10.355m and 10.24-10.27m is consistent with this interpretation. The hiatus covers the interval ca 12,800-11,600 yr B.P. There is a thin moss layer in 10.30-10.26m. Alm (1993) considers this indicates quite shallow water, ca 11,600- 10,600 yr B.P. The uppermost sediment (10.26-10.00m, unit E) is silty gyttja, suggesting increased water depth. The green algae assemblage is characterised by abundant planktonic species, such as Pediastrum, Tetraedron, Scenedesmus and Botryococcus, consistent with deep water. A relatively low sedimentation rate (0.05 cm/yr) is consistent with this interpretation. The unit is dated to ca 10,600-10,000 yr B.P. In the status coding, (0) indicates a possible hiatus; very low (1) is indicated by silty gyttja with high organic content and poor state of Pediastrum preservation; or by moss layer; low (2) by gyttja with no Pediastrum and high organic content; moderately low (2) by gyttja with indistinct lamination, high organic materials, and decline in Pediastrum; intermediate (3) by laminated gyttja and high organic content; moderately high (4) by laminated organic silt and abundant Pediastrum; high (5) by laminated silty gyttja with planktonic green algae assemblage and low sedimentation rate. There is no record for the Holocene, but we can code the present as moderately high (4) since the level is 6m higher than during the interval between 18,300 and 15,000 yr B.P. (Alm, 1993), which is coded as intermediate, moderately low to low (3, 2 and 1). Radiocarbon dates T-8022A 10,430±140 10.125-10.165m, silty gyttja, core E T-8023A 11,640±230 10.24-10.27m, moss, core E T-9421A 12,750±125 10.305-10.355m, mineral gyttja, core E T-9422A 14,730±165 10.50-10.57m, mineral gyttja, core E T-8024A 15,260±130 10.84-10.89m, gyttja, core J T-8567A 16,010±140 10.98-11.02m, gyttja, core J T-8025A 14,100±220 11.38-11.42m, gyttja, core J, small sample, REJECTED. T-8565A 16,210±140 11.60-11.65m, gyttja, core J T-8026A 16,820±250 11.82-11.87m, gyttja, core J T-8027A 17,590±130 12.17-12.22m, gyttja, core J T-8564A 17,490±150 12.40-12.45m, gyttja, core B T-8563A 17,790±130 12.60-12.65m, gyttja, core B T-8562A 18,060±180 12.81-12.85m, gyttja, core B T-8561A 18,000±170 12.99-13.03m, gyttja, core B T-8028A 17,800±260 13.275-13.325, gyttja, core K T-8028B 17,410±170 13.275-13.325, gyttja, core K T-8560A 17,740±270 13.37-13.395m, gyttja, core K T-8559A 18,820±200 13.57-13.62m, gyttja, core K T-8558A 19,650±180 13.675-13.725, gyttja, core K T-8029A 21,800±410 13.875-13.94, silty gyttja, core K T-8029B 21,520±150 13.875-13.94, silty gyttja, core K Note: Sub-samples with different pretreatments are indicated by A (NaOH-soluble) and B (NaOH- insoluble). References Alm, T., 1993. øvre Æråsvatn - palynostratigraphy of a 22,000 to 10,000 BP lacustrine record on Andøya, northern Norway. Boreas 22: 171-188. Vorren, T., Vorren, K-D., Alm, T., Gulliksen, S. and Løvlie, R., 1988. The last deglaciation (20,000 to 11,000 BP.) on Andøya, northern Norway. Boreas 17: 41-77. Vorren, K-D., 1978. Late and middle Weichselian stratigraphy of Andøya, north Norway. Boreas 7: 19-38. Coding ca 22,000-21,000 yr BP. moderately high (4) ca 21,000-18,300 yr BP. high (5) ca 18,300-17,900 yr BP. intermediate (3) ca 17,900-16,800 yr BP. moderately low (2) ca 16,800-16,100 yr BP. low (1) ca 16,100-15,100 yr BP. moderately low (2) ca 15,100-12,800 yr BP. very low (1) ca 12,800-11,600 yr BP. hiatus (0) ca 11,600-10,600 yr BP. very low (1) ca 10,600-10,000 yr BP. high (3) 0 yr BP. moderately high (4) Preliminary coding: 28/3/1994; Final coding: 28/4/1994. Coded by GY and SPH Pølsa, Norway Pølsa (74 30'N, 18 56'E, 14.0m above sea level) is a shallow lake in the northern part of Bjørnøya Island, Norway. The lake area is ca 14ha and the water depth is ca 1m. There is a outlet stream, and the distance to the coast is approximately 500m. The lake lies on a plain (ca 35m above sea level) that is thought to be a marine abrasion surface of Quaternary age but pre-dating the last glaciation (Hyvärinen, 1968). The elongated bedrock depressions in this surface, now occupied by lakes like Pølsa and Skinkevatna, are probably the results of glacial erosion. There are no prominent raised beaches younger than the last glaciation (Hyvärinen, 1968), which indicates that Bjørnøya has not been affected by isostatic rebound. The bedrock in the Pølsa catchment is Palaeozoic sandstone and limestone. A single 110cm-long core, taken from a depth of 1m, provides a sedimentary record back to ca 10,000 yr B.P. (Hyvärinen, 1968). The lake-level changes are reconstructed from changes in lithology and diatom assemblages. The chronology is based on pollen correlation with nearby radiocarbon-dated sites (Hyvärinen, 1968, 1970; Olsson, 1968): Skinkevatna (core B12), ca 400m to the southeast; Trullvatnet (core S7) in Nordaustlandet and Strøen (core S28) in Spitsbergen, ca 40-60 km far from Pølsa. The basal sediments in the core (below ca 105cm) are coarse mineral deposits. There is clayey silt with angular pebbles between ca 105-100cm. Hyvärinen (1968) suggests that these unsorted basal deposits may represent glacial debris deposited during the late glacial. The overlying sediment (100-90cm) is silty mud, suggesting relatively shallow water. The diatom assemblage is dominated by epiphytic species (total percentage of 81% at ca 92cm), mostly Fragilaria pinnata (77%), consistent with shallow conditions. The unit belongs to pollen zone I (below 87cm in the core), and is dated to before ca 9430 yr B.P. The overlying sediment (90-50cm) is sulphide mud with banded sections. This change in lithology could reflect deeper water, and the onset of anoxic conditions within the basin. Hyvärinen (1968) argues that the basin is quite shallow, so that it is unlikely that sulphide mud deposition was due to a phase of meromixis. He suggests that the lake has a low oxidation capacity because it is ice-covered most of the year, and that the episode of sulphide mud deposition may therefore reflect a period of greater-than-present organic input which could not be oxidised during the ice-free period. This explanation seems unlikely because loss-on-ignition is lower during the interval of sulphide deposition than in the over- or underlying units. Furthermore, the interval during which the lake was ice-covered is likely to have been shorter during the mid-Holocene, which implies that the opportunity for sediment oxidation would have been greater (consistent with the loss-on-ignition data) rather than less or similar to today (as implied by Hyvärinen argument). We therefore interpret the banded sulphide-rich deposits a indicating deep water. The diatom assemblage is characterised by an increase in benthic species (21% at 70cm; 36% at 85cm), such as Amphora ovalis (10-18%), and a slight decrease in epiphytes from 81% to 64%, consistent with increased water depth. The unit is dated to ca 9430-4000 yr B.P., based on pollen zones of IIa (60cm) and IIb (40cm) in the core which are dated to 5000 yr B.P. and 3000 yr B.P. respectively (from Hyvärinen, 1968; 1970). The uppermost sediment (0-50cm) is silty mud. The coarser lithology and absence of sulphide-banding suggest shallow water. The diatom assemblage is dominated by epiphytic species of Fragilaria spp. (91%) and there is a marked decline in benthics (to 9%), consistent with shallow water. The unit is date to the last ca 4000 yr B.P. based on the dating of pollen zone II/III boundary (17cm) to ca 2000 yr B.P. (from Hyvärinen, 1968; 1970). In the status coding, low (1) is indicated by silty mud with epiphytic diatoms dominant; high (2) by banded sulphide mud, and abundant benthic diatoms. Radiocarbon dates U-2301 11,200±500 yr B.P. pollen zone I, core B12, Skinkevatna. U-2064 8900+1200-1000 yr B.P. pollen zone I, core B12, Skinkevatna. U-2042 8300+1400-1200 yr B.P. pollen zone I, core B12, Skinkevatna. St-2534 11135±130 yr B.P. pollen zone I, core S28, Strøen. St-2454 10255±875 yr B.P. pollen zone I, core S28, Strøen. St-2776 6485±100 yr B.P. pollen zone IIa, core S7, Trullvatnet. St-2453 7240±200 yr B.P. pollen zone IIa, core S7, Trullvatnet. St-2665 5550±140 yr B.P. pollen zone IIa, core S7, Trullvatnet. St-2666 4745±120 yr B.P. pollen zone IIb, core S7, Trullvatnet. U-2050 4600+1200-1000 yr B.P. pollen zone IIb, core B12, Skinkevatna. Hel-40 2010±130 yr B.P. pollen zone II/III, core S7, Trullvatnet. References Hyvärinen, H., 1968. Late-Quaternary sediment cores from lakes on Bjørnøya. Geografiska Annaler 50 (A): 235-245. Hyvärinen, H., 1970. Flandrian pollen diagrams from Svalbard. Geografiska Annaler 52 (A): 213-222. Olsson, I. U., 1968. Radiocarbon analyses of lake sediment samples from Bjørnøya. Geografiska Annaler 50 (A): 246-247. Coding pre ca 9430 yr B.P. low (1) ca 9430-4000 yr B.P. high (2) ca 4000-0 yr B.P. low (1) Preliminary coding: 20/2/1994; Final coding: 25/2/1994 Coded by GY and SHP Saudedalsmyra, Norway Saudedalsmyra (ca 62.4 N, 6.4 E, 30m above sea level) is a bog on the island Sula in the Ålesund area on the west coastal region of Norway. The bog lies in the undulating coastal strandflat area (10-50m above sea level). The site was formerly a lake but became infilled in the Holocene (Kristiansen et al., 1988). The bog is ca 100m across. There is an inflow eastwards from TorvlØmyra to Saudedalsmyra bog, ca 50m away, but a bedrock sill separates the two basins of TorvlØmyra and Saudedalsmyra (Mangerud, per. comm. 1992). There is an outlet westwards to the sea. The catchment bedrock is granodioritic gneiss (Gjelsvik, 1951). The Ålesund area was deglaciated after ca 12,500-12,300 yr B.P. (Kristiansen et al., 1988); Saudedalsmyra became isolated from the sea ca 11,1500 yr B.P. (Kristiansen et al., 1988). The stratigraphy of the basin deposits has been reconstructed from 2 transects of 11 cores (Kristiansen et al., 1988). A ca 8.3m-long core (core 502-31-01/02/03) from the deepest part near the centre of the basin provides a sedimentary record back to before 11,500 yr B.P. (Kristiansen et al., 1988). The other cores show the same stratigraphy as core 502-32-01/02/03. The basal sediments (Formation B) are marine sediments. The record after the Boreal (above ca 3.8m in the core) has not been studied. Although the authors do not reconstruct changes in water depth, they do state that the changes in sediment composition are primarily a reflection of climate changes (Kristiansen et al., 1988). Changes in water depth are reconstructed from changes in lithology, aquatic pollen and algal assemblages. The chronology is based on two radiocarbon dates from the lacustrine sediments and five dates from the marine sediments (Kristiansen et al., 1988). The basal sediments of sandy silt (8.28-7.64m, Formation A), and silt and clay (7.64-5.19m, Formation B) are marine, and date to before 11,130±140 yr B.P. (Kristiansen et al., 1988) The overlying sediment (5.19-5.11m, the Åse Member) is lacustrine silty gyttja with low organics (10-20%), suggesting moderately deep water. The aquatic pollen is characterised by Potamogeton and Sparganium. There is abundant Pediastrum, consistent with deep conditions. A sample from the bottom of this unit is radiocarbon dated to 11,130±140 yr B.P. (T-3958A). The overlying sediment (5.11-5.00m, the Leirstad Member) is diatomite-silt, suggesting deep water conditions. The unit still contains low organics (10-20%) and high Pediastrum, consistent with deep water, ca 10900-10400 yr B.P. The uppermost unit (above 5.00m, the Hatlen Formation) is fine detritus gyttja, covering the entire Holocene (Mangerud, pers. comm., 1992). Between 5.00 and 4.20m the organic content increases to ca 50%, suggesting decreased water depth. The aquatic pollen is characterised by an increase in Potamogeton, Myriophyllum, and Sparganium, consistent with decreased water depth. A sample from the unit (ca 4.40-4.45) is radiocarbon dated to 8830±130 (T-3953A). A further decrease in water depth is indicated by increase in organic content to 80-90% (4.20-3.80m, the middle part of the Hatlen Formation). The disappearance of Pediastrum and Botryococcus, decline in Myriophyllum, and appearance of Menyanthes and abundant Equisetum, are consistent with decreased water depth after ca 8400 yr B.P. Kristiansen et al. (1988) did not study the upper part of the Hatlen Formation (above 3.80m), but they mentioned that the lake became infilled after the early Holocene. We assume the lake was infilled during the Boreal pollen zone (Kristiansen et al., 1988), ca 7600 yr B.P. based on an approximate sedimentation rate of 0.50 mm/yr. In the status coding, low (1) is indicated by gyttja with high organics, no Pediastrum or Botryococcus, and abundant Equisetum; intermediate (2) by gyttja or silty gyttja with increase in Potamogeton, Myriophyllum, Sparganium, abundant Pediastrum and Botryococcus; high (3) by diatomite-silt with low organic content and high Pediastrum. The uppermost deposits probably reflect natural infilling and are accordingly not coded. Radiocarbon dates T-3953A 8830±130 ca 4.40-4.45m, gyttja T-3958A 11130±140 ca 5.15-5.20m, silty gyttja T-3956C 11960±90 ca 5.90-6.00m, marine sediments T-3956A 12320±120 ca 5.90-6.00m, marine sediments, ATO? T-3956B 12350±140 ca 5.90-6.00m, marine sediments, ATO? T-4116A 12310±140 7.58-7.64m, shells, ATY T-3951A 12800±100 7.00-7.10m, marine sediments Note: The depths of the first 5 samples are not given in Kristiansen et al. (1988) but approximate depths have been assessed from Figure 20 (Kristiansen et al., 1988). References Gjelsvik, 1951. Oversikt over bergartene i SunnmØre og tilgrensede deler av Nordfjord. Norges Geologiska Undersokelse 179: 45 pp. Kristiansen, I.L., Mangerud, J. and LØmo, L., 1988. Late Weichselian/early Holocene pollen- and lithostratigraphy in lakes in the Ålesund area, western Norway. Review of Palaeobotany and Palynology 53: 185-231. Mangerud, J., Lie, S.E., Furnes, H., Kristiansen, I.L. and LØmo, L., 1984. A Younger Dryas ash bed in Western Norway, and its possible correlations with tephra in cores from the Norwegian Sea and North Atlantic. Quaternary Research 21: 85-104. Mangerud, J., 1992. personal communication. Letter. Coding ca 11300-10900 yr B.P. intermediate (2) ca 10900-10400 yr B.P. high (3) ca 10400-8830 yr B.P. intermediate (2) ca 8830-8400 yr B.P. low (1) ca 8400-0 yr B.P. not coded Preliminary coding: 6/11/1994; Final coding: 28/11/1994. Coded by GY and SPH Skinkevatna, Norway Skinkevatna (74 29'N, 18 55'E, 19.3m above sea level) is a shallow lake in the northern part of Bjørnøya Island, Norway. The lake area is ca 40ha and the water depth is ca 1.5m. There is a outlet stream, and the distance to the coast is approximately a kilometre. The lake lies on a plain (ca 35m above sea level) that is thought to be a marine abrasion surface of Quaternary age but pre-dating the last glaciation (Hyvärinen, 1968). The elongated bedrock depressions in this surface, now occupied by lakes like Skinkevatna, are probably the results of glacial erosion. There are no prominent raised beaches younger than the last glaciation (Hyvärinen, 1968), which indicates that Bjørnøya has not been affected by isostatic rebound. The bedrock in the Skinkevatna catchment is sandstone and limestone. A single ca 1m-long core (core B12) taken from the lake provides a sedimentary record back to ca 10,000 yr B.P. (Hyvärinen, 1968). The lake-level changes are based on changes in lithology, diatom and aquatic pollen assemblages. Three samples from core B12 have been radiocarbon dated (Hyvärinen, 1968; Olsson, 1970). Because of the presence of old carbon (coal) in the system and the possibility of contamination, separate assays of the humic and non-humic fractions were made. Three assays on the near-basal sample (92.5-87.5cm) yielded ages of 11,200±500, 8900+1200-1000 and 8300+1400-1200 yr B.P. Olsson (1968) points out that the difference between these dates is not significant (<2ó). We have therefore used an average of the humic and non-humic fractions to provide a date for this interval (9750 yr B.P.). The humic fraction of a sample from 42.5-37.5cm was dated to 4600+1200-1000 yr B.P. The statistical errors are large, but the date is consistent with the near basal sample. The uppermost sample (22.5-17.5cm) had an extremely low organic content and was subject to such a large dilution that the statistical errors are greater than 2000 years. We therefore do not use this sample to establish a chronology for the site. The basal sediments (below 102cm) are coarse mineral deposits. There is reddish clayey silt with angular pebbles between 102-90cm. Hyvärinen (1968) suggests that these unsorted basal deposits may represent glacial debris deposited during the late glacial. The overlying sediment (90-70cm) is greenish silty mud, suggesting relatively shallow water. The diatom assemblage is characterised by abundant epiphytic species (47-56% at 90-75cm), most of which is Epithemia sorex (27-39%), consistent with shallow conditions. The presence of abundant Equisetum is consistent with this interpretation. This unit is dated to after ca 9750 yr B.P. The overlying sediment (70-25cm) is dark sulphide mud with banded sections. This change in lithology could reflect deeper water, and the onset of anoxic conditions within the basin. Hyvärinen (1968) argues that the basin is quite shallow, so that it is unlikely that sulphide mud deposition was due to a phase of meromixis. He suggests that the lake has a low oxidation capacity because it is ice-covered most of the year, and that the episode of sulphide mud deposition may therefore reflect a period of greater-than-present organic input which could not be oxidised during the ice-free period. This explanation seems unlikely because loss-on-ignition is lower during the interval of sulphide deposition than in the over- or underlying units. Furthermore, the interval during which the lake was ice-covered is likely to have been shorter during the mid-Holocene, which implies that the opportunity for sediment oxidation would have been greater (consistent with the loss-on-ignition data) rather than less or similar to today (as implied by Hyvärinen's argument). We therefore interpret the banded sulphide-rich deposits as indicating deep water between 7690 and 2870 yr B.P. Biological variations recorded in this unit allow sulphide mud to be subdivided. Between 70-45cm, the diatom assemblage is characterised by dominance of benthic species (50-68%), such as Amphora ovalis (16% at 60cm) and Pinnularia interrupta (18% at 70cm), and a decrease in epiphytes (26-44%), consistent with deep water. A gradual decrease in Equisetum (55-40cm) is consistent with deepening. The unit is characterised by a peak in pollen density; good preservation is consistent with deep water. Between 45-25cm, the percentages of Fragilaria pinnata reach 30-50%, and epiphytic diatoms are dominant (71-60%), suggesting decreased water depth. The increase in Sphagnum (45-25cm) supports this hypothesis. A sample from the unit is radiocarbon-dated to 4600+1200, -1000 yr B.P. (U-2050, 42.5-37.5cm). The subunit boundaries (45-25cm) are dated to ca 5120 and ca 2870 yr B.P. respectively. The uppermost sediment (0-25cm) is silty mud. The coarser lithology and absence of sulphide-banding suggest shallower water. The diatom assemblage is dominated by epiphytic species of Fragilaria pinnata (54-43%) and a decline in benthics (28-36%), consistent with shallow water during the last ca 2870 yr B.P. In the status coding, low (1) is indicated by silty mud with abundant epiphytic diatoms; intermediate (2) by banded sulphide mud, moderate epiphytic diatoms (Fragilaria pinnata); high (3) by banded sulphide mud with benthic diatoms dominant. Radiocarbon dates U-2031 11200±500 yr B.P. 92.5-87.5cm, humus fraction. U-2064 8900+1200-1000 yr B.P. 92.5-87.5cm, insoluble remains. U-2042 8300+1400-1200 yr B.P. 92.5-87.5cm, gas obtained by wet combustion after extraction of humus. U-2050 4600+1200-1000 yr B.P. 42.5-37.5cm, humus. U-2049 6000+3100-2200 yr B.P. 22.5-17.5cm, humus. ATO, REJECT. References Hyvärinen, H., 1968. Late-Quaternary sediment cores from lakes on Bjørnøya. Geografiska Annaler 50 (A): 235-245. Hyvärinen, H., 1970. Flandrian pollen diagrams from Svalbard. Geografiska Annaler 52 (A): 213-222. Olsson, I. U., 1968. Radiocarbon analyses of lake sediment samples from Bjørnøya. Geografiska Annaler 50 (A): 246-247. Coding ca 9750-7690 yr B.P. low (1) ca 7690-5120 yr B.P. high (3) ca 5120-2870 yr B.P. intermediate (2) ca 2870-0 yr B.P. low (1) Preliminary coding: 15/12/1993; Final coding: 25/2/1994. Coded by GY and SHP Torvlømyra, Norway Torvlømyra (ca 62.4 N, 6.5 E, 35m above sea level) is a bog on the island Sula in the Ålesund area on the west coastal region of Norway. The bog lies in the undulating coastal strandflat area (10-50m above sea level). The site was formerly a lake but became infilled in the Holocene (Kristiansen et al., 1988). The bog is ca 100m across. There is an outlet westwards to Saudedalsmyra bog, ca 50m away, but a bedrock sill separates the two basins of TorvlØmyra and Saudedalsmyra (Mangerud, per. comm. 1992). There is an inflow to TorvlØmyra from the mountain slope to the south. As a result, the southern part of basin still has water but it is very shallow. (Kristiansen et al., 1988). The catchment bedrock is granodioritic gneiss (Gjelsvik, 1951). The Ålesund area was deglaciated after ca 12,500-12,300 yr B.P. (Kristiansen et al., 1988); TorvlØmyra became isolated from the sea ca 11,900 yr B.P. (Kristiansen et al., 1988). The stratigraphy of the basin deposits has been reconstructed from 5 cores (Kristiansen et al., 1988). A ca 7.4m- long core (core 502-32-01) from the central bog provides a sedimentary record back to before 12,000 yr B.P. (Kristiansen et al., 1988). The other cores show the same stratigraphy as core 502-32-01. The basal sediments (Formation B) are marine sediments. The record after the Boreal (above ca 5.65m in the core) has not been studied. Although the authors do not reconstruct changes in water depth, they do state that the changes in sediment composition are primarily a reflection of climate changes (Kristiansen et al., 1988). Changes in water depth are reconstructed from changes in lithology, aquatic pollen and algal assemblages. The chronology is based on six radiocarbon dates from the lacustrine units (Kristiansen et al., 1988). The basal sediments (7.50-7.02m in core 502-32-01, Formation B) are marine, and date to pre-11,900 yr B.P. (Kristiansen et al., 1988) The overlying sediment (7.02-6.48m, the Åse Member) is lacustrine silty gyttja. The lower part (7.02-6.85m, ca 11,900-11,600 yr B.P.) is low in organic matter (ca 10-20%) and contains no plant remains, suggesting moderately deep water. The aquatic pollen is characterised by Potamogeton and Nymphaea, consistent with deep water. Pediastrum, Botryococcus and Tetraedron in abundance are consistent with deep conditions. Two fractions of a sample from 6.90-7.00m are radiocarbon dated to 11,780±80 and 11,750±120 yr B.P. (T-3554 A and B) respectively. The upper part of this unit (6.85-6.48m, ca 11,600-11,300 yr B.P.) has abundant plant remains and organic content increases (up to 40%), suggesting decreased water depth. A leaf of Salix cf. polaris occurs at 6.74m and Equisteum is present in abundance, consistent with shallow conditions. Pediastrum decreases and Tetraedron gradually disappears, also consistent with decreased water depth. A sample from the top of the unit is radiocarbon dated to 11,340±120 yr B.P. (T-3954 A). The overlying sediment (6.48-6.17m, the Leirstad Member) is diatomite-silt and is characterised by a decrease in organic content (<10%), suggesting moderately deep water. A layer (5-23cm thick) of volcanic ash (identified as the Vedde Ash) occurs within this unit. It is considered to be inwashed from the catchment rather than in situ (Mangerud, pers. comm., 1992). The ash is faintly laminated, suggesting it was deposited in deep water. The Vedde Ash Bed is radiocarbon-dated to 10,680±80 yr B.P. (Mangerud et al., 1984). Samples from the bottom and top of this unit are radiocarbon dated to 10,640±70 (T-3960) and 10,430±110 yr B.P. (T-4585) respectively. The uppermost unit (above 6.17m, the Hatlen Formation) covers the entire Holocene (Mangerud, pers. comm., 1992). In the lower part of the Hatlen Formation, the sediments are light brown gyttja. The aquatic pollen (ca 6.17- 5.95m) is characterised by an increase in Potamogeton, Myriophyllum, Menyanthes and Sparganium, suggesting shallow water. The top of this sub-unit is correlated with the Preboreal/Boreal pollen zones, and assumed to occur ca 8900 yr B.P. (Kristiansen et al., 1988). The middle part of the Hatlen Formation is darker brown gyttja. The aquatic pollen (ca 5.95-5.65m) is characterised by a decrease in Myriophyllum, Menyanthes and Sparganium, and an increase in Potamogeton and Nymphaea, suggesting increased water depth after ca 8900 yr B.P. Kristiansen et al. (1988) mention that the sediments around 5.60m are coarse gyttja and state that the lake became infilled after the early Holocene. The coarse gyttja can be correlated to the Boreal pollen zone (Kristiansen et al., 1988), suggesting the basin began to infill after ca 8400 yr B.P. In the status coding, low (1) is indicated by silt gyttja with organic content ca 40%, abundant plant remains, and low abundances of Pediastrum, Botryococcus and Tetraedron; intermediate (2) by silt gyttja with organic content ca 20%, no plant remains and Pediastrum, or by gyttja with increase in Menyanthes and Sparganium; moderately high (3) by gyttja with decrease in Menyanthes and increase in Potamogeton; high (4) by diatomite- silt with low organic content (<10%) and laminated structure. The coarse gyttja and peat in the top of the lake deposition reflect natural infilling and are accordingly not coded. Radiocarbon dates T-3959 9170±90 ca 6.20-6.25m, inwashed material from Vedde Ash Bed, ATY? T-3952A 10430±110 ca 6.12-6.17m, gyttja T-3960 10640±70 ca 6.35-6.37m, inwashed material from Vedde Ash Bed T-3954A 11340±120 ca 6.47-6.50m, silty gyttja T-3553B 11750±120 ca 6.90-7.00m, silty gyttja T-3553A 11780±80 ca 6.90-7.00m, silty gyttja Note: The depths of samples are not given in Kristiansen et al. (1988) but approximate depths have been assessed from Figure 19 (Kristiansen et al., 1988). References Gjelsvik, 1951. Oversikt over bergartene i SunnmØre og tilgrensede deler av Nordfjord. Norges Geologiska Undersokelse 179: 45 pp. Kristiansen, I.L., Mangerud, J. and LØmo, L., 1988. Late Weichselian/early Holocene pollen- and lithostratigraphy in lakes in the Ålesund area, western Norway. Review of Palaeobotany and Palynology 53: 185-231. Mangerud, J., Lie, S.E., Furnes, H., Kristiansen, I.L. and LØmo, L., 1984. A Younger Dryas ash bed in Western Norway, and its possible correlations with tephra in cores from the Norwegian Sea and North Atlantic. Quaternary Research 21: 85-104. Mangerud, J., 1992. personal communication. Letter. Coding ca 11900-11600 yr B.P. intermediate (2) ca 11600-11300 yr B.P. low (1) ca 11300-10400 yr B.P. high (4) ca 10400-8900 yr B.P. intermediate (2) ca 8900-8400 yr B.P. moderately high (3) ca 8400-0 yr B.P. not coded Preliminary coding: 17/10/1994; Final coding: 24/11/1994 Coded by GY and SPH Belle Lake, Ireland Belle Lake, Ireland 148 145 Cannons Lough, Ireland Cannons Lough, Ireland Coolteen, Ireland Coolteen, Ireland Cregganmore, Ireland Cregganmore, Ireland Sheeauns, Ireland Sheeauns, Ireland Castiglione, Italy Castiglione, Italy Fucino, Italy Fucino, Italy Lago di Ganna, Italy Lago di Ganna, Italy Endletvatn, Norway Ellasjøen, Norway Endletvatn, Norway Endletvatn, Norway Lerstadvatn, Norway Lerstadvatn, Norway Nedre Æråsvatn, Norway Nedre Æråsvatn, Norway øvre Æråsvatn, Norway øvre Æråsvatn, Norway Pølsa, Norway Pølsa, Norway Saudedalsmyra, Norway Saudedalsmyra, Norway Skinkevatna, Norway Skinkevatna, Norway Torvlømyra, Norway Torvlømyra, Norway