Geologic Tour of New Mexico — Physiographic Provinces

Storrie Lake State Park is located four miles north of Las Vegas, New Mexico, and can be reached via New Mexico Highway 518. The 1400-foot long earthen dam that retains the water in Storrie Lake was built under the direction of Robert C. Storrie starting in 1916. Water from the Gallinas River, a southeasterly-flowing river with its headwaters in the Sangre de Cristo Mountains and the main water supply for the community of Las Vegas, is diverted for storage in Storrie Lake. The park offers camping, boating, fishing, beaches, and other water-related activities.

Storrie Lake State Park lies on the boundary between two important physiographic provinces, the Southern High Plains and the Southern Rocky Mountains. The lake is on the High Plains just east of the Rincon Range portion of the Sangre de Cristo Mountains, a sub-province of the Southern Rocky Mountains.

This small park, established in 1916 by presidential proclamation, offers a close-up view of one of the most perfectly preserved cinder cones in North America. The road to the summit provides access to the summit crater, and if you have ever wanted to walk into a volcano, Capulin Mountain is one of the few places you can do so. A 0.2-mile-long trail from the summit parking lot descends to the vent at the bottom of the crater. The view from the crater rim encompasses all of northeastern New Mexico as well as parts of Texas, Oklahoma, and Colorado.

Heron Lake State Park is located approximately 9 miles west of Tierra Amarilla. Heron Dam was built on Willow Creek near its confluence with the Rio Chama in 1971. This earth fill dam, which is 276 feet tall and 1221 feet long, is designed to create a reservoir to store and deliver San Juan-Chama Project water. The water is used to maintain the recreation pool at Cochiti Lake, some 120 miles downstream on the Rio Grande. The San Juan-Chama Project, managed by the Bureau of Reclamation, takes water from tributaries of the San Juan River, which lies to the west of the Continental Divide, to augment the natural flow of the Rio Grande, which is east of the Continental Divide. The water flows through the Azotea Tunnel under the Continental Divide to Willow Creek, then to Heron Reservoir and the Rio Chama, a tributary of the Rio Grande. The diversions began in 1970, delivering an annual average of 94,200 acre-feet of water to the Rio Grande. Water users include the City of Albuquerque, the City of Santa Fe, the Middle Rio Grande Conservancy District, and the U.S. Department of Energy. The lake can hold 399,980 acre-feet at a crest elevation of 7,192 feet. Heron Lake State Park has been designated a "quiet lake", where boats travel at "no-wake" speeds.

The Chino mine, an open-pit porphyry copper mine, is 15 miles east of Silver City near the village of Hanover in southwestern New Mexico). An overlook of the pit, complete with educational displays, is located on the south side of New Mexico Highway 152 east of Hanover. The excavation is also known as the Santa Rita Mine or Santa Rita del Cobre, named for the former village of Santa Rita, which was removed in the 1950s as mining operations in the area expanded. Concern has been expressed about the stability of the famed landmark on the southeast side of the mine, the spire known as the Kneeling Nun, as the modern-day mining operation moves to the southeast. The Chino mine is the largest porphyry copper deposit in New Mexico. The pit is currently ~1.75 miles across and 1,350 feet deep. The Apaches were the first to notice native copper lying on the ground in a valley northwest of Santa Rita Mountain. The open-pit mining operation began in 1910. The mine became part of Freeport-McMoRan in 2007.

Mount Taylor volcano, a prominent landmark that can be seen on the skyline west of Albuquerque, is located about 15 miles northwest of the town of Grants, New Mexico. Mount Taylor Peak, at an elevation of 11,301 feet, stands approximately one mile above the Rio San Jose 12 miles to the south. Mount Taylor volcano is part of a larger, northeast-trending volcanic field that includes Mesa Chivato, a broad plateau located northeast of the cone, and Grants Ridge, located southwest of the cone. Basalt that caps Mesa Chivato and other mesas surrounding Mount Taylor makes up about 80% of the volume of the volcanic field. The Mount Taylor volcanic field lies on the southern flank of the San Juan Basin on the Colorado Plateau and straddles the extensional transition zone between the Colorado Plateau and the Rio Grande rift. The Mount Taylor volcanic field is considered to be part of the Jemez Lineament, a zone of young (< 5 million years old) volcanism aligned along an ancient suture in the 1.7 to 1.6 billion year old Proterozoic basement.

Smokey Bear Historical Park is in the center of the town of Capitan. In May 1950, a raging forest fire blackened approximately 17,000 acres of the Capitan Mountains in the Lincoln National Forest in central New Mexico. As forest fire fighters brought the blaze under control, a small black bear cub was found clinging to the remains of a charred tree. First aid was administered to the badly burned bear cub and he was sent to Santa Fe for further treatment. Although the fire fighters didn’t realize it then, a national symbol had been born. The story of the bear cub was told in newspapers and on radio throughout the country. The cub, named Smokey Bear, went to the National Zoo in Washington, D. C. and became the living symbol for fire prevention. Through many successful campaigns, Smokey not only was responsible for reducing the number of man-made forest fires but he also raised more than $27 billion through donations in the past 40 years.

Hyde Memorial State Park lies in the southwestern Sangre de Cristo Mountains in the Santa Fe Range. The north-south trending Sangre de Cristo Mountains are about 225 miles long, extending from near Salida, Colorado, at the north end to just southeast of Santa Fe at the south end (Bauer, 2008). The Sangre de Cristo Mountains are considered to be part of the Southern Rocky Mountain physiographic province. The mountains rise abruptly from the relatively topographically subdued High Plains on the east side. The Rio Grande rift, a northerly-trending zone of continental extension that runs from northern Colorado to west Texas, marks the western boundary of the range. The Santa Fe Range, which is cored by Proterozoic basement rocks, is bound on the north by the Peñasco embayment, on the south by Glorieta Pass, on the west by the Española Basin, and on the east by the Picuris-Pecos Fault just west of the Pecos River. At least four episodes of mountain building are recorded in the Sangre de Cristo Mountains.

El Vado (“the ford”) Lake lies upstream of a place along the Rio Chama in north central New Mexico where a resistant sandstone ledge in the upper part of the Cretaceous Dakota Sandstone crosses the river. The narrow canyon through this sandstone ledge facilitated passage across the Rio Chama prior to construction of El Vado dam. The Middle Rio Grande Conservancy District completed the construction of El Vado dam in 1935 to store irrigation water in order to honor Native American water rights of the six Middle Rio Grande Pueblos. The dam was updated in 1953-1954 and the outlets were modified in 1965-1966 to accommodate increased flows associated with San Juan-Chama Project.

Ghost Ranch is located approximately 38 miles northwest of the town of Española, New Mexico, just north of U.S. Highway 84, and is run by the Presbyterian Church as a conference center. It has facilities for lodging and camping, as well as paleontology and cultural museums. It lies in the Chama Basin, a broad shallow basin along the eastern margin of the Colorado Plateau in the transition between the Plateau and the Rio Grande rift.

The Valles Caldera National Preserve is one of the most geologically unique and significant areas in North America. The preserve encompasses much of the Valles caldera, a huge volcanic crater that formed 1.2 million years ago during an enormous volcanic eruption that spread ash over large parts of New Mexico. The caldera is located near the summit of the Jemez Mountains, a large volcanic complex in north-central New Mexico. The Valles caldera exhibits world-class examples of the landforms produced by a very large, explosive volcano, and the preservation and exposure of geological features within the Valles is spectacular. Much of what geologists know about large-scale explosive volcanism began with detailed studies of the rocks in the Valles caldera and Jemez Mountains, and the area continues to draw geologists from around the world. Since the eruption 1.2 million years ago, there has been uplift of the crater floor, followed by the eruption of smaller, younger volcanoes called “domes” within the crater left by the large eruption. Since then, the caldera has from time to time been home to a series of large lakes. This dynamic geological history is responsible for the beautiful and unique landscape that we see in the region today.