Geologic Tour of New Mexico

Sevilleta National Wildlife Refuge (NWR) is located in central New Mexico about 15 miles north of Socorro. The refuge spans the Rio Grande valley from the Sierra Ladrones on the west to the Los Pinos Mountains on the east, an area of approximately 30 miles by 15 miles, encompassing 230,000 acres. The area was designated a Spanish land grant, Sevilleta de la Joya, in 1819. The land grant was sold in 1928 to Socorro County and then, in 1936, to General Thomas D. Campbell, under whom it became a ranch for sheep and cattle. The Campbell Family Foundation donated the land to the Nature Conservancy in 1973, which then passed it on to the U.S. Fish & Wildlife Service to become a national wildlife refuge dedicated to preservation and enhancement of the integrity and natural character of the land. The transfer stipulated that the land should undergo natural processes of succession, including floods and fires, without human interference. Thus, most of the refuge has very limited public access, but the Mesa View Trail west of the Visitor Center is open for hiking at least five days per week.

Pancho Villa State Park in Columbus, New Mexico, was established in 1959 “in interest of preservation of the memory of the unique, historical occasion of the last hostile action by foreign troops within the continental United States”. It became the only park in the United States to be named after a foreign invader. The creation of the 60-acre park was a gesture of good will between the United States and Mexico. The town of Columbus has been designated a National Historic Site. Across the street from the park is the privately owned Pancho Villa Museum.

Aztec Ruins National Monument was established in 1923 to preserve the remarkable remains of an ancestral Puebloan farming community, including a twelfth-century Chacoan great house. The settlement flourished from A.D. 1050–1150, at which time it was one of the largest Puebloan settlements in the Southwest, strategically situated between Mesa Verde to the north and Chaco Canyon to the south. Culturally it is considered a Chacoan outlier, at the northern terminus of one of the prehistoric roads that emanated from Chaco. Later occupants (in the 1200s) are thought to have had closer ties to Mesa Verde.

One of the earliest written eyewitness accounts of Aztec Ruins was provided by geologist John Newberry in 1859, who reported at that time that the walls stood 25 feet high. Both the ruins and the setting are spectacular, but the park is perhaps best known for the reconstructed Great Kiva, which was excavated in 1921 and reconstructed by Earl Morris in the 1930s. It is the only restored great kiva in the Southwest and is accessible to visitors; stepping inside provides a unique glimpse of what these ceremonial structures might have been like when they were intact. The park is now a World Heritage Site.

The Gilman Tunnels are on NM 485 along the Rio Guadalupe in the southwestern Jemez Mountains, approximately 5 miles northwest of the intersection of NM 4 and NM 485. Two narrow and unusually high tunnels were cut through Precambrian granite in the 1920s to facilitate passage of logging trains through this particularly rugged and constricted section of Guadalupe Canyon, known as the Guadalupe Box. Logs that were harvested in the western Jemez Mountains in the 1920s were taken by narrow-gauge railroad to a sawmill in Bernalillo. The tunnels were enlarged in the 1930s to accommodate logging trucks. Logs were hauled out of the mountains and then loaded on trains at Gilman logging camp, which was established in 1937 about two miles south of the tunnels. The railroad was shut down by flooding along the Jemez and Guadalupe Rivers in 1941. The highway now occupies the old railroad bed. Aside from providing access to the Guadalupe Box itself, NM 485 provides an unparalleled view of the stratigraphy of Guadalupe Canyon.

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.

Oliver Lee Memorial State Park, at the mouth of Dog Canyon on the western escarpment of the Sacramento Mountains, opened in 1980, but the area has attracted visitors for several thousands of years. The 180-acre state park has a flowing stream and forms an oasis on the edge of the harsh desert of the Tularosa (Spanish, "reddish willows") Valley. The park is named for Oliver Lee (1865-1941), a prominent rancher and state legislator who settled near the mouth of Dog Canyon in the late 1880s. Lee was active in developing water-control projects in the area. Oliver Lee's ranch is one of the many exhibits at the state park. The Visitor's Center houses displays of the geologic and cultural history of the canyon area. Approximately 30,000 people enjoy camping, hiking, and picnicking in the park each year. An interpretative trail along lower Dog Canyon allows visitors a glimpse of vegetation and wildlife in the oasis as well as several cultural sites. The Dog Canyon Trail starts at an elevation of about 4,500 ft in the state park and climbs the steep escarpment of the Sacramento Mountains to the Eyebrow Trail to Joplin Ridge at an elevation of 7,753 ft, for a total one-way distance of about six miles.

Organ Mountains–Desert Peaks National Monument is a large, diverse and recently established park. It has four separate geographic areas: the Organ Mountains, the Doña Ana Mountains, the Potrillo Mountains, and the “Desert Peaks." This tour deals only with the Organ Mountains. The geology of the Doña Mountains area is briefly discussed in the tour of Fort Selden–Leasburg Dam. The Potrillo Mountains include the remote Potrillo volcanic field and are covered in the Kilbourne Hole tour. The "Desert Peaks" includes the Robledo Mountains and Sierra de las Uvas. The Robledo region is described in the tour of the "Prehistoric Trackways National Monument" (a separate, but contiguous national monument).

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.

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.

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.