LONG-TERM PATTERNS OF ENVIRONMENTAL AND CLIMATE CHANGE INFERRED FROM LITHOSTRATIGRAPHIC AND BIOSTRATIGRAPHIC RECORDS

Geoarchaeological studies document long-term patterns of Quaternary landscape evolution and human-environment interactions. Sediments associated with archaeological and paleontological assemblages in North Africa and western North America can be used to infer landscapes resulting from past climates. Stratigraphic sequences from southern Egypt provide evidence of lakes and playas associated with Paleolithic and Neolithic archaeological sites. Coarse siliciclastics (chiefly quartz sands) interpreted as eolian or redeposited eolian deposits, reflect arid climates or the initiation of a wet phase in a climate cycle, while limestones or marls imply the presence ponds and lakes formed under wetter conditions. Acheulian and Middle Paleolithic artifact assemblages are associated with lake and playa settings in the Bir Tarfawi region and Neolithic assemblages at Nabta are found with fine-grained siliciclastics interpreted as playa deposits. Taxonomic and geochemical studies of fossils recovered from the North African localities provide independent evidence for environmental change linked to changing climates, perhaps at the glacial-interglacial time scale. In western North America, lithostratigraphic and biostratigraphic data collected to support geoarchaeological or Quaternary paleontological studies also provide a means to infer paleoenvironments that can be related to climate change, including the last glacial-interglacial transition, the Younger Dryas, and the Altithermal. The Barrow Pit locality in Blackwater Draw, in New Mexico, may reflect changing environments on the Southern High Plain associated with Late Glacial climates, including evidence for a “Clovis drought” and deposits dating to the time of Folsom artifacts. Localities in Montana also provide evidence for environmental change in the northern Rockies and Plains that appear to indicate climate change. Stratigraphic sequences at Sheep Rock Springs, Indian Creek, MacHaffie, Blacktail Cave, Marias River, Deer Creek and OTL Ridge are late Quaternary sedimentary records of environmental conditions. These localities, investigated for their geoarchaeological or paleocological potential, contain lithostratigraphic and biostratigraphic evidence of landscape response that can be correlated with past climate change.