Paleo Slide Set: Climate and the Classic Maya Civilization
Oxygen isotopic ratio of rainfall/groundwater, Lake Chichancanab & Lake Punta Laguna.

This bar chart shows measurements of the oxygen isotopic ratio of modern rainfall and groundwater 
(blue and magenta) compared to lake water from Chichancanab (white) and Punta Laguna (yellow). 
The oxygen isotopic composition of precipitation and groundwater averages -4 per mil (1/1000). 
Lake Chichancanab averages +4 per mil, indicating that it is 8 per mil enriched in 18O due to 
evaporation of lake water. Lake Punta Laguna averages +1 per mil, indicating about a 5 per mil 
enrichment. These results indicate that a significant amount of water received by Lakes Punta 
Laguna and Chichancanab is lost to evaporation annually, thereby enriching the lake water in 18O. 

Photo Credits:
David A. Hodell 
Department of Geology, University of Florida