THE BLOG – RED ROCK
Keystone Thrust Fault
Geology: As you look at the escarpment to the west you see older gray Paleozoic limestone resting on top of the younger buff and red Jurassic sandstone. This is a result of the Keystone Thrust Fault. Near the end of the Mesozoic Era, about 65 million years ago, the oceanic plate began “subducting” (moving beneath) the western edge of the North American Plate. This resulted in the intrusion of the Sierra Nevada granite batholith, which set up compressional forces in the Earth’s crust that caused the older limestone to be thrust east up and over the younger sandstone. The limestone cap served to protect the weaker sandstone from erosion for millions of years, eventually eroding back to its present location.
Aztec Sandstone
Geology: About 180 million years ago the area was completely arid, much as the Sahara Desert is today. A giant dune field stretched from Red Rock Canyon NCA eastward into Colorado, and windblown sand piled more than a half mile deep in some locations. As the wind shifted the sands back and forth, old dunes were leveled and new ones built up, leaving a record of curving, angled lines in the sand known as crossbeds. These shifting sands were buried by other sediments and eventually cemented into sandstone by iron oxide with some calcium carbonate. This formation, known locally as the Aztec Sandstone, is quite hard and forms the prominent cliffs of the Red Rock escarpment. Exposure to the atmosphere led to the iron minerals in some areas to oxidize, giving the rocks their red and orange colors.
The red color of some of the outcrops of the Aztec Sandstone is due to presence of iron oxide or hematite. Exposure to the elements caused iron minerals to oxidize or “rust,” resulting in red, orange, and brown-colored rocks. Areas where the rock is buff in color may be places where the iron has been leached out by subsurface water, or where the iron oxide was never deposited.
limestone
Geology: 600 million years ago, the land that is now Red Rock Canyon NCA was at the bottom of a deep ocean and the coast was in present day western Utah. A rich variety of marine life flourished in those waters and left behind deposits of shells and skeletons more than 9,000 feet thick. These were eventually compressed into limestone and similar carbonate rocks.
Starting approximately 225 million years ago, crustal movements caused the sea bed to slowly rise. Streams entering the shallower waters deposited mud and sand which later consolidated into shale and marine sandstone. Changing land and sea levels also trapped large bodies of water. These later evaporated, leaving behind layers of salt and gypsum in some areas.
Limestone is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, and forms when these minerals precipitate out of water containing dissolved calcium.
The La Madre Mountains Wilderness area is an example of Limestone in the Red Rock Canyon National Conservation Area.
Biology
Red Rock Canyon National Conservation Area is one of the easternmost parts of the Mojave Desert; the lowest elevation of the area, from 3,600 to 4,500 feet is in the Lower Sonoran Zone, while the area from 4,500 feet up is in the Upper Sonoran Zone. The character of the sandstone layers is such that several year-round springs may be found in the recesses of the side canyons.
Some 600 species of plants are known in the area. Common types in the valley floor include the Joshua tree, Mojave Yucca, Banana Yucca, Creosote, and Blackbrush. Higher up the Utah juniper and Sonoran scrub oak come to dominate. Agave is easy to spot in red rock niches, with its thick, low leaves and flowering stem reaching twice a man’s height. The Calico Tanks trail has a plaque about prehistoric agave roasting pits. Ponderosa pines may be found at the top of the valley, where it connects to the Spring Mountains.
Native Americans
History: The first humans were attracted to the Red Rock area due to its resources of water, plant, and animal life that could not be easily found in the surrounding desert. Hunters and gatherers such as the historical Southern Paiute (900 A.D. to modern times), Patayan Culture (900 A.D. to early historic times in the 1800s), Ancient Puebloans (1 A.D. to 1150 A.D.) and the Pinto/Gypsum (Archaic 3,500 B.C. to 1 A.D.) have successively occupied this area. The above dates are approximate and subject to debate.
Rock Art is a reminder of the past and comes in two varieties, Petroglyphs and pictographs. The difference between the two types is the manner in which they were made. Petroglyphs were pecked into the surface of the rock. Pictographs were painted on the rock. In Red Rock Canyon, a coating of dark “desert varnish” on lighter sandstone provides the perfect medium for petroglyphs, which are the most common of the two types of rock art found at Red Rock Canyon. The Cottonwood Valley and Brownstone Basin have the best rock art in the Red Rock Canyon area.
Modern History
History: Red Rock was visited by the Spanish in 1776, bringing with them cultural changes, and from 1829-30 Antonio Armijo led the first successful round trip trade caravan from Santa Fe to the Pueblo De Los Angeles. Armijo and his scouts mapped the trade route, which became the Old Spanish Trail. Old Spanish Trail kiosks are located at the State Route 159 Overlook and Late Night parking lot along State Route 160.
In 1844 and 1845, Fremont retraced the path of the Old Spanish Trail in 1844 and 1845 by following the accounts of earlier explorers. Maps of Fremont’s route were distributed in the east and the route became a popular alternative for travelers wishing to avoid the Sierra Nevada during winter or those headed to southern California. Traffic increased after gold was discovered in California in 1848. The route eventually became known as the Mormon Road due to the number of Mormon settlers traveling from Salt Lake City, Utah to San Bernardino, California.
As the early settlers passed through the area, they also discovered the canyon and finally homesteaded in this meadow. The items remaining from the early settler’s use of this area are part of the cultural resources you see today. Settlers, initially few in number, used transportation routes and homesteaded in this area over the years. They brought with them non-native plants and domesticated animals into these areas.
Recent History
History: Horace and Glenna Wilson, early homesteaders diverted water from Pine Creek for a large garden. They grew sweet potatoes, beans, melons, strawberries, blackberries, grapes, and peaches – all non-native plants.
By the early 1900s, sandstone was quarried in what is now Sandstone Quarry. During the 1930s the Civilian Conservation Corp was active building wildlife guzzlers in Red Rock. The evidence of modern cultural history can be found in the ruins of buildings and quarrying sites at Red Spring, Sandstone Quarry, La Madre Spring and Pine Creek.
In 1967, the Bureau of Land Management designated 10,000 acres as the Red Rock Recreation Lands. In 1973, the U.S. House of Representatives subcommittee on Federal Conservation Areas held a special hearing in the Foley Federal Office Building in downtown Las Vegas to review a legislative resolution sponsored by Nevada’s lone Congressman, David Towell (R-NV) to establish the Red Rock Conservation Area by transferring Federal land to the State of Nevada. Testimony in favor of the bill was given by the Sierra Club and a high school student and environmental activist, Dennis Causey. The subcommittee unanimously approved the resolution, sending it to the full Committee on the Interior and subsequently to the full House, followed by favorable action by the U S. Senate and approval by President George H. W. Bush. Further legislation in 1990 changed the status of the Red Rock Recreation Lands to a National Conservation Area, a status that also provides funds to maintain and protect it. The Federal area was adjacent to the Red Rock State Park.
