The volcanic field caps the Santa Ana Mesa and many north-south trending faults cut the volcanic rocks. Initial activity was explosive.
Basalt flows from fissure eruptions created much of the volcanic field.
There are also shield-shaped vents, dozens of cinder cones, plugs, dikes, and cone sheets. The volcanoes erupted about 2.6 to 2.5 million years ago. It is made of tephra, flows, sills, dikes, and cone sheets. The San Felipe volcanic field is about 15 km northeast of Albuquerque in the Santo Domingo Basin and only a few kilometers south of the south edge of the Jemez Mountains . Photo courtesy of Geoffrey Johnson.