Volcanism is evident nearly everywhere you travel in New Mexico. Some places it’s more evident than others. Capulin volcano is one of the more obvious places.
Travel about 30 miles southeast from Raton toward Clayton and you’ll drive through a volcanic field of about 100 volcanoes that formed nine million years ago. Most of the volcanoes blend in with neighboring mountains. Capulin is different.
First, it’s much younger, the result of an eruption that occurred about 56,000 years ago. Secondly, it formed on plains that once had been beds of shallow inland seas, so it stands out, sort of like a wart in the middle of your hand. It’s a classic shield volcano — a rounded cone with steep sides and a distinct crater.
Capulin began when the ground fractured, the crack reaching a magma chamber deep in the earth. Pressurized magma now had a way to escape to the surface, often violently. Molten rock the consistency of toffee and impregnated with gas exploded to the surface. It cooled quickly to become what we call cinder or pumice. The constant stream of cinder falling to earth formed the cone above the vent. Rock falling into the crater would plug the vent — that is, until pressure built up and the volcano once again exploded. Prevailing winds from the southwest tended to cause a larger buildup on the northeasterly side of the developing cone causing the crater’s lopsided appearance.
During its history, the volcano experienced a succession of four different lava flows, separated by thousands of years. But, instead of blowing out the crater, these flows oozed through weak spots at the base of the volcano, covering 15 square miles in the process. As the crust cooled and lava continued to flow underneath, ripple marks formed on the surface perpendicular to flow direction. Lava mounds called tumuli, or squeeze-ups, also formed where the crust broke and lava spewed out under pressure.
Eventually, the pressure was relieved enough that explosive events ceased. Then it entered its next phase of life. Lichens formed on the exposed rock and commenced building soil. Eventually plants and trees took root to create a unique biodiversity on the steep slopes and surrounding lava fields of the volcano. Because of the quick vegetative growth, the mountain retained its original appearance without the extensive erosion found on its neighbors.
Undoubtedly, Capulin served as a landmark for travelers, sitting as it does 1,800 feet above the surrounding plains. Paleoindians roamed the area, as noted by the archaeological evidence found at Folsom, eight miles to the north. Utes, Jicarilla Apache, and other native people hunted through the area.
Diaries reveal conquistadors Francisco Coronado and Juan de Padilla rode passed Capulin, beginning the cultural transformation brought by Europeans, first the Spanish and later the Americans. The Cimarron Cutoff of the Santa Fe Trail passed 20 miles south of the volcano, which would have served as a guide to travelers.
Cowboys drove herds along the Goodnight-Loving Trail to sell to the army at Fort Sumner. Livestock not sold was driven north past Capulin to markets in Colorado. Finally in 1916, President Woodrow Wilson created the Capulin Volcano National Monument. It achieved its protected status because the Department of the Interior considered it to be the perfect specimen of North American volcanoes. Through it all, Capulin has slept — for more than 40,000 years now. But it’s not extinct. Scientists record it merely as dormant.
Today, visitors can drive to the summit. The two-mile-long roadway built in 1925 spirals up the side of the cone. At the top, you can can take in the endless views of surrounding plains and distant mountain ranges. That would be enough for most. But there are also two trails from the summit parking lot. One takes you 400 feet to the bottom of the crater. The other makes a complete loop around the top. Benches and informational plaques are strategically placed along the path, telling the history of the volcano and identifying the four different lava flows.
Capulin Volcano National Monument has a $7 per car entrance fee. It is open daily (its next scheduled closing is Thanksgiving) from 8 a.m. to 4:30 p.m. The visitor center offers exhibits on both human history and natural history. More information is available on line at nps.gov/cavo.