Raton-Clayton (Capulin Volcano) Volcanic Field

Location: 36 to 37.3 degrees N latitude, 103.1 to 104.3 degrees W longitude Type: Extensive volcanic field of scoria cones, silicic volcanoes, and lava flows Age: 9 million years to 40,000 years Significance: Large and young monogenetic scoria cones; extreme diversity of lava compositions from very mafic to dacitic.

The Raton-Clayton field is one of the best examples of a large volcanic field in the world. Volcanic fields differ from the more popular conception of volcanoes, like Hawaii or Mount St. Helens. Instead of one big volcano, volcanic fields are clusters of many small volcanoes (up to 2 miles across). Volcanic fields are usually 60 or more miles across, and contain tens to several hundred separate volcanoes. Each volcano consists mainly of cinders, spatters, and dark lava flows. The volcanoes do not all form at the same time. Instead, several thousand years may pass between the eruption and formation of each volcano. Volcanic fields represent many eruptions spaced out over a period of several million years.

The Raton-Clayton volcanic field (RCVF) is the eastern-most Cenozoic volcanic field in the United States. To the east, Cenozoic volcanic rocks are not encountered at this latitude again until the mid-Atlantic ridge. [As an interesting note and insight into the absence of appreciation of local geologic features common in most areas of the world: The town of Clayton publicizes the nearby occurrence of dinosaur tracks at Clayton Lake State Park, yet ironically makes no mention of its location near the eastern end of one of the eastern-most, young, and largest volcanic fields in the North American contnent!

The volcanic field covers nearly 7500 square miles of northeastern New Mexico and adjoining Colorado and Oklahoma. The distinctive characteristic of the Raton-Clayton field is its great size, young age, continental interior setting, and possible association with one of the few volcanic hot spots in the world. If you start traveling east, you would not encounter volcanic rocks this young again until the mid-Atlantic ridge. The lava compositions are also somewhat unusual. And it is the site of Capulin Volcano, the eastern-most young and easily accessible volcano in North America.

The Raton-Clayton volcanic field is best known to historians as the site of some of the best preserved segments of the Santa Fe trail. Famous landmarks on the trail such as Round Mound, Wagon Mound, and Rabbit Ears Mountains are all volcanic centers. The field is of note because it lies at the northeastern end of the "Jemez lineament", a prominent alignment of volcanic fields extending from the Pinacate field of Mexico, through the Springerville field on the southern margin of the Colorado Plateau in eastern Arizona; the Zuni-Bandera field and the Mount Taylor fields near Grants, western New Mexico; the Jemez field and Cerros del Rio Fields near Santa Fe; and terminating in the northeastern corner of New Mexico in the Raton-Clayton field. Because the alignment of fields in the Jemez lineament is parallel to the Snake River-Yellowstone volcanic hot spot track, the Jemez Lineament has been considered by some volcanologists to be a type of volcanic "hot spot". Hot spots are rare, unlike the very common and explosive type of volcanoes like Mount St. Helens. Only 49 volcanic "hot spots" are recognized by volcanologists in the world. A few other famous volcanic hot spots include the Azores, Reunion Island, Iceland, Hawaii, and parts of East Africa.

The oldest rocks range from about 9 million years old, and the youngest erupted as little as 45,000 years ago. The earliest lavas of the Raton-Clayton field flowed onto the surface of sediment shed eastward from the Sangre de Cristo Mountains. Continuing uplift during eruption resulted in the erosion of this surface where it was not capped by volcanic rocks. During subsequent eruptions, lava flowed down valleys cut between the lava caps. The result is a series of "inverted topographic valleys" such that the oldest volcanic rocks are now found at the highest elevations above present erosional levels, with younger lavas at progressively lower levels. The most recent volcanic activity occured at several volcanoes in the center of the field in the vicinity of Capulin Mountain, where lava flows have moved down current drainages.