San Felipe volcanic field, also called the Santa Ana Mesa field, is a monogenetic volcanic field in New Mexico north of the confluence of the Jemez River and the Rio Grande. Rather than a single mountain, it is a broad volcanic landscape of lava flows, fissures, vents, and cinder cones formed about 2.5 million years ago by tholeiitic basalt erupting across relatively flat ground. Its largest fissure created the San Felipe shield volcano, and the field also contains three other major eruption centers and 66 cinder cones. Later erosion and regional uplift left the basalt-capped volcanic terrain standing as a high mesa above the Jemez River.