Geologic Tour of New Mexico

Kilbourne Hole in south-central New Mexico is a classic example of a maar crater that formed as a result of the explosive interaction of hot basaltic magma with groundwater during a volcanic eruption. When the steam-saturated eruption column that forms during an explosive event gravitationally collapses, a ring-shaped surge travels radially outward along the ground away from the vent. The stratified, cross-bedded pyroclastic surge deposits around the crater at Kilbourne Hole are spectacular. The surge deposits may have formed as a consequence of a series of steam explosions during the emplacement of the basalt.

Kilbourne Hole is unique because of the remarkable abundance of both crustal and mantle (peridotite/olivine-bearing) xenoliths that are in basalt bombs ejected during the eruption. Xenoliths are inclusions of pre-existing rock derived from country rocks, in this case, pieces of mantle and crust, that were incorporated into the mafic magma as it moved from a depth of about 40 miles (60 km) to the surface.

Morphy Lake State Park offers fishermen, campers, hikers, and other visitors a rustic alpine setting in the Sangre de Cristo Mountains. Spectacular views are the result of complex geologic processes active since Proterozoic time (1,700 m.y. ago): two major periods of mountain building (called orogenies) and most recently erosion and sedimentation by glaciers and rivers.The state park is 7 miles southwest of Mora and 3 miles northwest of Ledoux in the eastern Sangre de Cristo Mountains in northern New Mexico. It is the least accessible of the New Mexico state parks.

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 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.

Tsiping, also called Tsi’pin or Tsi’pinouinge, is a remarkable pueblo ruin located on Pueblo Mesa near the village of Cañones in the northern Jemez Mountains. Although the site is on Santa Fe National Forest land, the site is off limits unless you have a permit. Permits can be obtained from the Coyote Ranger Station.

Tsi’pinouinge means “village of the flaking stone”, a reference to the village’s proximity to lithic-source quarries in the Pedernal Chert on Cerro Pedernal. Based on tree-ring measurements and ceramic styles, Tsiping was occupied between 1200 AD and 1325 AD, during the Classic Period. Tsiping was the northernmost and largest of the Classic Period pueblos. The village had somewhere between 335 to 400 ground floor rooms, sixteen kivas, and a central plaza. Cavate dwellings are located on the southeastern side of the mesa.

Fort Selden State Monument is adjacent to Leasburg Dam State Park on NM–157 (Fort Selden Road) at the Radium Springs exit on I–25, north of Las Cruces. It is an area rich in both geologic and human history. The location was an ancient Indian campground and a crossing point for Spanish caravans headed across the Jornada del Muerto. Living-history demonstrations of 19th century military life at Fort Selden highlight many weekends during the summer. Wildlife viewing, especially bird watching, is popular at the state park. A bird list is available from the park office. In the winter months many species of ducks, teals, snow geese, cranes, herons, egrets, swans, and pelicans migrate through the southern Rio Grande valley and can be seen at the state park. Numerous raptors, including owls, turkey vultures, eagles, and hawks, can be seen hunting in the area. Small mammals common to the park include rabbits, squirrels, chipmunks, rodents, coyotes, and foxes.

Cabezon Peak is one of the best-known and most visible landmarks in northwest New Mexico. This giant volcanic plug is visible for tens of miles in all directions, and as far away as Placitas. Cabezon means “big head” in Spanish, and it is aptly named. It is the largest of several dozen widely scattered rocky monoliths, called the Rio Puerco necks. Rising above the Rio Puerco valley floor, they are some of the best-preserved examples of volcanic necks in the world. The craggy black peaks stand in sharp contrast to the sparsely vegetated, buff-colored lowlands from which they emerge. Mt. Taylor looms majestically to the southwest, Mesa Prieta borders the valley to the east, and the Jemez Mountains are visible to the north. This starkly beautiful landscape is unique in New Mexico. At an elevation of 7,786 ft, Cabezon Peak towers more than 1,100 ft above its base, and 2,000 ft above the Rio Puerco nearby.

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.

The Tyrone mining district, the second largest porphyry copper deposit in New Mexico, is located 10 miles southwest of Silver City in the Burro Mountains of southwestern New Mexico. Native Americans initially mined turquoise from the area around 600 AD. Underground mining was established in the early 1860s and the current mode of mining, open-pit stripping, began in 1968. The mine became part of Freeport-McMoRan in 2007. Parts of the pit are currently being reclaimed.

The country in northwestern New Mexico between Cuba and Farmington is a land of contrast. Flat grassy plains are cut by valleys that expose the multi-colored moonscapes that we call badlands. The largest area of badlands in the region that is readily accessible to the public is the Bisti/De-Na-Zin Wilderness, popularly known as the Bisti Badlands. The badlands are generally exposed in a series of east to west-trending valleys formed by the tributaries that feed to the south to the north-flowing Chaco River.

The many fossils preserved in this region make this one of the best places on Earth to study the fascinating story of the end of the age of dinosaurs and the beginning of the age of mammals. These fossils will not be obvious to casual visitors, but visitors will be instantly struck by the spectacular scenery of this area, which has been featured in books, magazines, calendars, and websites.