Late Quaternary environmental change in the Bonneville Basin, Western USA

TitleLate Quaternary environmental change in the Bonneville Basin, Western USA
Publication TypeJournal Article
Year of Publication2001
AuthorsMadsen DB, Rhode D, Grayson DK, Broughton JM, Livingston SD, Hunt J, Quade J, Schmitt DN, Shaver IIIMW
JournalPalaeogeography Palaeoclimatology Palaeoecology
ISBN Number0031-0182
Accession Number2001-030960
Keywords24 Quaternary geology, California, Cenozoic, Chordata, Climate Change, floral studies, Lake Bonneville, lake-level changes, Mammalia, Nevada, Oregon, paleoclimatology, paleoenvironment, Quaternary, Tetrapoda, United States, upper Quaternary, Utah, Vertebrata, Western U.S.

Excavation and analyses of small animal remains from stratified raptor deposits spanning the last 11.5 ka, together with collection and analysis of over 60 dated fossil woodrat midden samples spanning the last 50 ka, provide a detailed record of changing climate in the eastern Great Basin during the late Pleistocene and Holocene. Sagebrush steppe dominated the northern Bonneville basin during the Full Glacial, suggesting that conditions were cold and relatively dry, in contrast to the southern basin, which was also cold but moister. Limber pine woodlands dominated approximately 13-11.5 ka, indicating increased dryness and summer temperatures approximately 6-7 degrees C cooler than present. This drying trend accelerated after approximately 11.5 ka causing Lake Bonneville to drop rapidly, eliminating 11 species of fish from the lake. From approximately 11.5-8.2 ka xerophytic sagebrush and shadscale scrub replaced more mesophilic shrubs in a step-wise fashion. A variety of small mammals and plants indicate the early Holocene was approximately 3 degrees C cooler and moister than at present, not warmer as suggested by a number of climatic models. The diversity of plants and animals changed dramatically after 8.2 ka as many species disappeared from the record. Some of the upland species returned after approximately 4 ka and Great Salt Lake became fresh enough at approximately 3.4 and approximately 1.2 ka to support populations of Utah chub.