Geologic Tour of New Mexico

he Ship Rock landform, located in northwestern New Mexico, is the remnant of an explosive volcanic eruption that occurred around 30 million years ago. The main part of the landform is 600 meters high, and 500 meters in diameter. Ship Rock, known as Tse Bitai, or "the winged rock" in Navajo, is a volcanic neck, or the central feeder pipe of larger volcanic landform which has since eroded away. The neck is composed of fractured volcanic rock, or breccia, crosscut by many thin veins of lava. Ship Rock is composed of an unusual, highly potassic magma composition called a "minette", thought to form by very small degrees of melting of the earth's mantle. Ship Rock was probably 750 to 1000 meters below the land surface at the time it was formed, and has since gained its prominent form due to erosion of surrounding rocks.

Santa Rosa, "the city of natural lakes", lies in the semiarid, upper Pecos River valley in Guadalupe County where numerous natural artesian-spring lakes abound. Blue Hole, one of these lakes located within the city limits, is well known for its crystal-clear water and attracts scuba divers. However, the largest lake in the area is man made—Santa Rosa Lake, located about seven miles north of the city on the Pecos River. The dam was completed in 1981 at a cost of $43 million for conservation of irrigation water and flood and sedimentation control. The name of the dam was changed from Los Esteros (Spanish for pond or estuary) in 1980 when the state park was authorized.

Percha Dam and Caballo Lake State Parks, located south of the town of Truth or Consequences, offer striking views of the Caballo Mountains and Red Hills, prominent uplifts in the southern Rio Grande rift. The Percha and Caballo dams were built for the Bureau of Reclamation’s Rio Grande Project in 1918 and 1936–38, respectively. Percha Dam, although only 18.5 feet tall, diverts water into the Rincon Valley, irrigating farmland where much of New Mexico’s famous green chile is grown, along with many other crops. Two miles upstream, the 96-foot-tall and 4,590-feet-wide earth-fill Caballo Dam stores water released from hydroelectric- power generation at Elephant Butte Dam and regulates delivery of that water to downstream users during irrigation season.

Oasis State Park lies 18 miles southwest of Clovis and 7 miles north of Portales via US–60 and NM–467. It was established in 1961 to preserve the natural beauty of a true oasis in the sandy desert of the Llano Estacado or “staked plains” of the Great Plains physiographic province. The surrounding area is flat, treeless, featureless, and relatively dry. The summers are hot, the winters are cold, the wind seems to blow constantly. In contrast, the park offers shade trees and a small lake, as well as conveniences such as water, showers, electric hookups, and dump stations expected of picnic areas and modern campgrounds. Many of the facilities are accessible to people with disabilities. In addition to picnicking and camping, fishing, hiking, and bird watching are popular activities. The pond is stocked with catfish and trout. Trails weave up and down and around the sand dunes; watch carefully for lizards, snakes, and other wildlife that make the sand their home! A ballfield lies near the center of the park and there is a new visitor’s center. The Blackwater Draw Museum is located east of Oasis State Park on US-70, and the Blackwater Draw Archaeological Site is north of the state park.

El Morro, which means "bluff" or "headland" in Spanish, is an imposing cliff made of Middle to Late Jurassic (155 to 165 million years old) Zuni Sandstone capped by Late Cretaceous Dakota (~95 to 96 million years old) sandstone and shale. Travelers, including Native Americans, Spaniards, and citizens of the United States, have carved their symbols, names, messages, and dates of their passage into the soft cross-bedded Zuni Sandstone for centuries.

Elephant Butte Lake State Park is located approximately 5 miles north of the town of Truth or Consequences. Elephant Butte Reservoir is on the Rio Grande in south-central New Mexico east of Interstate 25 between Socorro and Las Cruces. The 301-feet high and 1,674-feet long concrete dam across the Rio Grande that created Elephant Butte Reservoir is the largest dam in the state of New Mexico. Elephant Butte Reservoir was the largest man-made reservoir in the world when the dam was completed in 1916. The dam is considered a National Historic Civil Engineering Landmark, primarily because the construction of this dam marked the first civil engineering project designed for international distribution of water.

Conchas Lake State Park was established in 1955 and named after the Conchas River, one of the tributaries of the Canadian River. It is 24 mi north of Newkirk and 31 mi northwest of Tucumcari on NM–104 and NM–129. Conchas is Spanish for shells and was applied to a group of Indians living in the area when Spanish explorers arrived in the 17th century. The word conchas may be a corrupted name that is confused with the Spanish word conchos, a term also used to describe the Native American tribes in northern New Mexico.

The dam that formed Conchas Lake was the 17th dam in the country built by the U.S. Army Corp of Engineers. One of the state’s oldest dams, it was completed in 1939 to control floods, store water for irrigation and local supplies, and assist in local economic recovery from the Depression.

Petroglyph National Monument is located on Ceja Mesa on the west side of Albuquerque. The monument is best known for the estimated 25,000 rock art images carved into basalt erupted from the approximately 200,000-year-old Albuquerque volcanic field. Using stone chisels and hammer stones, the ancestors of the Puebloan Indians cut most of the petroglyphs into the desert varnish coating the basalt between 1300 and 1680 A.D. A few of the markings are much older, dating back to perhaps 2000 B.C. Spaniards and later generations of Albuquerque inhabitants have produced younger petroglyphs with more modern themes. The monument, created in 1990, includes about 17 miles of petroglyph-covered basalt cliffs and five extinct volcanoes.

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.

Angel Peak, a 7000-foot pinnacle capped by sandstone, is a prominent landmark near Bloomfield in northwestern New Mexico. It is in the northern part of the San Juan Basin, a large structural depression that formed starting about 75 million years ago during compressional Laramide deformation. The San Juan Basin was surrounded by mountainous uplifts to the north (now buried by the 35 to 20 Ma San Juan volcanic field in southwestern Colorado) and to the east that also formed by Laramide-related compression. The sediments that can be seen at Angel Peak National Recreation area were eroded off of the old Laramide highlands and deposited in the basin 50 to 65 million years ago. More recently, over the course of the last 5 million years (or less), the westward-draining San Juan River, a tributary to the Colorado River, has eroded the rocks of the San Juan Basin. Drainages feeding into the San Juan River have carved the scenic landscape we see today.