THE USE OF SEDIMENTARY SEQUENCES FROM ARCHAEOLOGICAL AND PALEONTOLOGICAL LOCALITIES TO EXAMINE CLIMATE CHANGE AND LATE QUATERNARY LANDSCAPE EVOLUTION (Invited Presentation)

Studies of Late Quaternary sedimentary sequences containing archaeological occurrences or fossils often focus on documenting site-specific depositional events in an effort to evaluate local formational and taphonomic processes, as well as to infer micro- or meso-environmental landscape contexts, such as topographic settings and landforms. Another potentially valuable application is to attempt to correlate the sedimentary sequences at the macro-environmental level, with the goal of developing regional-scale models of landscape evolution. As an example, sedimentary records from Late Quaternary stratigraphic sequences in the Northern Rocky Mountains and Great Plains provide an opportunity to interpret glacial and interglacial environmental conditions in the Upper Missouri River basin. Sedimentary sequences from Centennial Valley and Blacktail Cave in western Montana, and also the Doeden and Glendive localities along the Yellowstone River, contain Pleistocene fossil assemblages. In addition, these sequences provide a record of depositional processes that can be linked to regional- and global-scale climates. In the Yellowstone basin, the fossils are found in terrace gravels that have been correlated with glacial outwash processes. Other localities along the eastern front of the Rockies (such as Sheep Rock Spring, Indian Creek, MacHaffie, and Sun River) and on the Northern Great Plains (such as near the Marias River, as well as the Yellowstone River drainage at Lindsay/Deer Creek and OTL Ridge) contain stratigraphic sequences that can be interpreted as localized responses to final Pleistocene and Holocene climate changes. Tephras interbedded in some of these stratigrahic sequences provide a means of correlation, as do buried soils that may coincide with climate events such as the Younger Dryas. The Indian Creek and Marias sequences contain final Pleistocene and mid-Holocene tephras, and the Sun River locality contains a mid-Holocene tephra. Buried soils or deposits associated with "black mats" are present at MacHaffie, Lindsay/Deer Creek, and OTL Ridge. Chronometeric and biostratigraphic age constraints for these depositional sequences provide an opportunity to propose a regional-scale model of late Quaternary landscape evolution based on sedimentologic, geomorphic, and paleobiotic evidence.