[bert]

——there is little consensus———

It is clear to me that the onset caused massive disruption of human life in North America. The 1275 -1300 dating corresponds to the massive change in the South west and Cahokia.

The Anasazi moved from Aztec hundreds of miles south ti Paquim and split into the present Pueblo and Hopi settlements. Simultaneously, Cahokia fell apart and settlements south developed.

What ever it was that caused the chang turned human culture upside down and produced radical change in the way life was lived.

[blam]

"What ever it was that caused the chang turned human culture upside down and produced radical change in the way life was lived."

It is said that 250,000 'took to the sea' at the end of the Shang Dynasty.
I've often wondered because this is about the same time that the Olmec appears (very advanced) in Mexico. Maybe some of those Shang survivors?

The Olmecs An The Shang

[ApplegateRanch]

It is clear to me that the onset caused massive disruption of human life in North America. The 1275 -1300 dating corresponds to the massive change in the South west and Cahokia.

I've been seeing articles popping up lately touting Ubehebe Crater in Death Valley as last erupting only 800 years ago, rather than thousands, "with profound effects upon the Southwest...".

First thing that came to mind was the Anasazi.