The Great Basin itself is a vast interior drainage basin — water flows in but doesn’t flow out to the ocean — characterized by mountain ranges and intervening valleys, by lakes and marshes and desert.

The Snake River Plain, to the north, was shaped by repeated volcanic events over millions of years and by the catastrophic floods of the Pleistocene.

It is not the Great Basin proper, but it shares ecological and archaeological connections with it.

By the terminal Pleistocene, this region was in ecological transition.

The glaciers were retreating.

Pluvial lakes — lakes inflated by the higher rainfall and lower evaporation of the glacial period — were shrinking.

Megafauna were declining or had already gone extinct in many areas.