Boot Heel volcanic field  The Boot Heel volcanic field is located in the Bootheel region of southwest New Mexico, adjacent areas of southeastern Arizona, and northwest Mexico. The field covers an area of more than 24,000 km2. The field includes nine volcanic calderas ranging in age from 26.9 to 35.3 Ma. Extrusive products include rhyolitic ignimbrites along with basalt, andesite, and rhyolite lava flows. The major ash flow tuff sheets produced, range in volume from 35 to 650 km3. The field includes the Geronimo-Animas volcanic field and the Palomas volcanic field. The Geronimo volcanic field (also known as the San Bernardino volcanic field) is a monogenetic volcanic field and a sub-section of the Boot Heel volcanic field in southeastern Arizona, US. The calderas of the Boot Heel field include: