Geology and coal resources of the Stonewall-Tercio area, Las Animas County, Colorado

The Stonewall-Tercio area lies along the western edge of the Trinidad coal field, Colorado, a part of the large Raton Mesa region of Colorado and New Mexico. Coal of Upper Cretaceous and early Tertiary age in that region has been utilized extensively for coking and for domestic heating. Present mining operations are limited, but mining is possible throughout much of the field.