The Boot Heel volcanic field is located in the Bootheel region of southwest New Mexico, adjacent areas of southeastern Arizona, and northwest Mexico.

[2] The field includes nine volcanic calderas ranging in age from 26.9 to 35.3 Ma.

The major ash flow tuff sheets produced, range in volume from 35 to 650 km3.

[2] Activity throughout most of the Boot Heel volcanic field paused between 33 and 28 million years ago.

[3] The pause in activity has been interpreted as a period of tectonic reorganization along the west coast of North America, including the birth of the San Andreas Fault, that temporarily shifted volcanism to the east.