Fossil bison and artifacts from an early altithermal
period arroyo trap in Wyoming.
This may refer to the severe Altithermal
drought of 7500-8000 B.
The site is near Lake Huron and likely experienced a lowered ground water table until about 6,000 years ago at the end of the dry Altithermal period, when lake and ground water levels were lower throughout the Midwest.
Desiccation and fracturing were probably heightened in the Till Plains of Ohio during the dry Altithermal period (about 6,000 to 9,000 years ago) when prairies and grasslands of the Plains expanded eastward to central Ohio.
Significant environmental changes occured over the last 18,000 years, but the Altithermal period, around 7000 years ago, marks a punctuation in Aboriginal demographic, social and biological organization rather than a gradual process of social change.
and their attaining modern aspect after the Altithermal, 6000-8000 years ago, riverine resources would have increased.
archeology and paleoecology at Mustang Springs, on the Southern High Plains of Texas.
Apparently there was no warm-moist or dry Altithermal
interval in central Texas but rather a pronounced period of drier and possibly warmer conditions starting about 2000 years ago (Holloway et al.