The Bandelier Tuff near Los Alamos, New Mexico

The Bandelier Tuff near Los Alamos, New Mexico.  The Jemez Mountains, home to the Valles and Toledo calderas where the tuff originated, rise in the distance.  The tuff was hot and thick when it was deposited by caldera-forming eruptions 1.61 and 1.25 million years ago, and so it is welded in places, forming a dense and resistant rock.  USGS photo by Mike Poland, June 7, 2022.