Geologic Tour of New Mexico

The craggy gray granodiorite spire of Cookes Peak, the highest point in the Cookes Range at 8,404 feet, is a prominent landmark in southwestern New Mexico. Cookes Spring on the southeast side of the range is one of just a few perennial springs in this part of New Mexico; consequently, this peak was an important marker of water for Native American, Spanish, and American travelers through the region during the 19th century. The peak was named for Captain Phillip St. George Cooke, who led the Mormon Battalion through southern New Mexico during the winter of 1846 while scouting an overland wagon route for the U.S. Army. Later, a Pony Express mail station was established near the spring. Fort Cummings was built nearby in 1863 to protect travelers from Apache attacks; the fort was manned by the U.S. Army off and on until Geronimo surrendered in 1886. Ruins of the Cookes Spring Station of the Butterfield Trail and Fort Cummings are located about a mile south of the present-day Hyatt Ranch.

West of the flocks of birds and birdwatchers along the wetlands of the Rio Grande, a story of cataclysmic volcanic eruptions, ancient dune fields, and long-gone towering mountains lie quietly awaiting visitors to the Bosque del Apache National Wildlife Refuge. The Chupadera Wilderness Trail and the Canyon Trail traverse this geologic record in the contemplative solitude of a wilderness setting, affording “rockwatchers” a quick trip through millions of years of Earth history.

Brantley Lake State Park on the Pecos River was officially opened in November 1989. The park lies 12 mi north of Carlsbad via US–285. Brantley Lake is designed to hold 348,540 acre-ft of water. Although the primary functions of the lake are flood control and water storage for irrigation and water commitments to Texas and Mexico, the lake is best known for its water recreation and fishing. The most common fish stocked by the New Mexico Department of Game and Fish include largemouth bass, walleye, channel catfish, trout, sunfish, white bass, bluegill, and crappie. Brantley Wildlife Management Area lies south of the dam, as well as north of Brantley Lake, in the area once occupied by Lake McMillan. The Pecos River valley is a major waterfowl migration route, and many species of birds are present on and near the lake throughout the year.

A spectacular, eroded anticline and syncline pair lies between the Ojito Wilderness and the village of San Ysidro in north-central New Mexico. The San Ysidro area lies near the intersection of four significant geologic features, including the mildly deformed Colorado Plateau to the west, the Laramide-age (75 to 55 million years old) Sierra Nacimiento uplift to the north, and the late Oligocene to Miocene Rio Grande rift to east. The northeast-trending Jemez lineament, characterized by young volcanism, cuts across all three geologic provinces. The <15 million year old Jemez volcanic field is visible to the northeast, the 2 to 3 million year old Puerco Necks, including Cabezon Peak, are located just to the west, and the 1.5 to 3.3 million year old Mount Taylor volcano can be seen on the skyline to the west.

Sugarite Canyon State Park, once the site of a thriving coal-mining camp, was established as a state park in 1985, but the canyon has been a recreational attraction in northeastern New Mexico for decades. Sugarite Canyon State Park is located about 5 miles northeast of Raton via NM-72 and NM-526 (paved). The elevation in the park ranges from about 6,900 ft to 8,400 ft. This heavily wooded mountain park has something for everyone year round. Trails are maintained through the ruins of the settlement and past coal dumps and mines.

Bluewater Lake State Park lies at an elevation of 7,400 ft in Las Tuces Valley near the Continental Divide in the Zuni Mountains. The park is between Gallup and Grants along I–40, 7 mi southwest of Prewitt via NM-412. A forest of cottonwoods, piñon, and juniper surrounds the lake. The Navajos knew the area as “large cottonwood trees where water flows out” (Julyan, 1996). It became a state park in 1955. Bluewater and Cottonwood (Azul) Creeks feed the lake. The lake itself is formed by an arched dam 90 ft high and 500 ft long (Robinson, 1994) that impounds 38,500 acre-ft of water. The last time water spilled over the dam was in 1941. The dam is convex in the upstream direction for increased strength, and it is at the mouth of Bluewater Creek in a steep-walled canyon. An overlook at the end of the road through the park facilities offers an excellent view of the dam and canyon. A primitive hiking trail leads down into the canyon below the dam.

The New Mexico Department of Game and Fish maintains a permanent pool of water for fish and periodically stocks the lake with rainbow trout and channel catfish. Indeed, the lake is blue, as the name implies. It is well known to ice-fishermen during the winter. Power and sail boating, hiking, water skiing, wind surfing, and swimming are possible recreational activities in addition to fishing, camping, picnicking. Care should be taken driving in wet weather along the north side of the lake because of muddy conditions. Not all 25 mi of shoreline belong to the state park; some land surrounding the lake belongs to private individuals, Indian tribes, and U.S. National Forest. All water, however, is open to the public.

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).

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.

Kasha-Katuwe Tent Rocks National Monument is on the southeast side of the Valles and Toledo calderas, large collapse features that formed during voluminous eruptions in the Jemez Mountain volcanic field 1.61 and 1.25 million years ago. Tent Rocks encompasses a fascinating landscape in the southeastern Jemez Mountains. Kasha-Katuwe means 'white cliffs' in Keresan, the traditional language of the nearby Pueblo de Cochiti. Delicately layered sand, gravel, volcanic ash, and tuff of the Peralta Tuff Member of the Bearhead Rhyolite and sand and gravel of the Cochiti Formation, which are older units (2 to 6 Ma) in the Jemez Mountain volcanic field, have been erodedinto fragile to robust spires with balanced rocks perched on top. The hoodoos, erosional cones, and pedestal rocks that characterize Tent Rocks form as the result of differential erosion.

Cimarron is Spanish for wild and untamed and originally was used in New Mexico to refer to the wild bighorn sheep, and later to the wild horses and cattle that once roamed throughout the north-central mountains (Pearce, 1965). Today, the sparsely populated Cimarron country in western Colfax County can still be described as wild and untamed with its rugged, timbered mountains (the Cimarron Range), towering cliffs, and the previously unpredictable Cimarron River. The Cimarron River has been tamed somewhat by the Eagle Nest Dam, which controls flooding in the canyon.