Raton-Clayton and Ocate volcanic fields
— J. C. Aubele and Crumpler. L. S.

The Raton-Clayton (RCVF) and Ocate Volcanic Fields (OVF) constitute the most significant late Cenozoic volcanic activity east of the Rocky Mountains. A salient characteristic of volcanic fields is the relatively low volumetric rates of eruption compared with major volcanic centers. The RCVF consists of about 125 vents and, including outlying portions, covers nearly 20,000 km². Rocks range from about 9 Ma to less than 60,000 yrs, yielding a recurrence rate of approximately 1.3 X 10^-5 volcanic events per year. The RCVF can be divided into three main phases of volcanic activity: (1) Raton, which includes basalt flows and rhyodacite domes; (2) Clayton, which includes voluminous basalt flows and the Sierra Grande shield volcano; and (3) Capulin, which includes cinder cones and flows centered on Capulin Volcano National Monument. Although widely cited, the previous age estimate of less than 10,000 yrs for Capulin Volcano was based on an interpreted correlation, not an absolute date. Two dating techniques, the cosmogenic helium technique and the Ar-Ar technique indicate a date for Capulin of about 58,000 yrs. Three major series of lava flow units were erupted from Capulin, with the second and third series erupted from the base of the cone at the "boca". It is likely that the eruption of the hoca flow altered the profile of Capulin, subsequently its symmetry was restored by continued building of the cone. The Ocate Volcanic Field consists of at least 16 flows and about 50 associated vents ranging in age from 8.34±0.50 Ma to 0.81±0.14 Ma. Like the RCVF, three major topographic levels of lava flows relate to three age groups: (1) older than S Ma, which includes flows capping mesas with surfaces around 3000m in elevation and an apparent E-W fissure line of vents near Wagon Mound; (2) 5-4 Ma, which includes most of the flows around Agua Fria; and (3) younger than 4 Ma, which includes the most abundant flows in the OVF and such vents as Cerrito Felon, Cerro Negro, Cerro del Oro and Maxon Crater. Flows from Maxon flowed 90 km eastward along the canyon cut by the Mora River where they occur 100m below the rim of the canyon and 125m above the present level of the rivet The youngest flows in the field were erupted from Cerro del Oro, in the central part of Charette Mesa, northwest of Wagon Mound.