Paleo Slide Set: Packrat Middens: Vegetation & Climate Variability in the Southwestern United States
Bone of the giant camel, [Camelops sp.], found in a midden from the Garrison site.

As the name implies, packrats constantly collect all kinds of material to construct their 
dens and to store food. The contents of their middens are a fair representation of the local 
environment at the time the material was collected. For example, this midden from the Garrison 
site in western Utah contains objects gathered by a packrat some 13,480 14C years ago, including 
plants and animals that no longer exist at this site. The large mammal bone belongs to a camel 
(Camelops sp.) that became extinct about 12,500 years ago, though it was once widespread in western 
North America. The plant material found in the midden indicates that the vegetation at this site was 
once an open limber pine (Pinus flexilis) woodland. This site is just above the old terraces of Lake 
Bonneville, an enormous lake that covered parts of Utah, Nevada and Idaho during the last glacial period. 
During the Holocene, Lake Bonneville shriveled into what is now called the Great Salt Lake. From a modern 
perspective of the Great Salt Lake area, it may be hard to envision a menagerie of now-extinct herbivores, 
including giant camels, moving across the wooded shores of a huge, "interstate" lake. 

Photo Credits:
Robert S. Thompson 
U. S. Geological Survey