Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock containing 25% to 75% ash is described as tuffaceous. Tuff composed of sandy volcanic material can be referred to as volcanic sandstone.
The Colorado Plateau is a physiographic and desert region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. This plateau covers an area of 336,700 km2 (130,000 mi2) within western Colorado, northwestern New Mexico, southern and eastern Utah, northern Arizona, and a tiny fraction in the extreme southeast of Nevada. About 90% of the area is drained by the Colorado River and its main tributaries: the Green, San Juan, and Little Colorado. Most of the remainder of the plateau is drained by the Rio Grande and its tributaries.
The Powderhorn Wilderness is a 62,050-acre (251.1 km2) wilderness area in Hinsdale and Gunnison counties, Colorado, United States, located 5 miles (8.0 km) northeast of Lake City.
The Solitario is a large geologic formation in Big Bend Ranch State Park in West Texas. When viewed from above, it suggests an impact crater; though it is actually the eroded remains of a laccolith. The approximate center of the Solitario is located 56.8 km (35.3 mi) east southeast of Presidio, Texas, just west of the line dividing Brewster County, Texas and Presidio County, Texas. The formation covers a circular area of approximately 135 km2 (52 sq mi). The geology of the Solitario is complex. In 1988, the state of Texas purchased the property containing the Solitario and created Big Bend Ranch State Park.
Mount Lamborn is a mountain summit in the West Elk Mountains range of the Rocky Mountains of North America. The 11,402-foot (3,475 m) peak is located in Gunnison National Forest, 5.9 miles (9.5 km) southeast by south of the Town of Paonia in Delta County, Colorado, United States. The summit of Mount Lamborn is the highest point in Delta County. Together with nearby Landsend Peak to the southwest, it lies at the western edge of the West Elks, rising dramatically nearly 6,000 ft above the valley of the North Fork Gunnison River to the west.
Lizard Head is a mountain summit in the San Miguel Mountains range of the Rocky Mountains of North America. The 13,119-foot (3,999 m) thirteener is located in the Lizard Head Wilderness, 6.8 miles (11.0 km) west by south of the Town of Ophir, Colorado, United States, on the drainage divide separating San Juan National Forest and Dolores County from Uncompahgre National Forest and San Miguel County.
Crested Butte is a prominent mountain summit in the Elk Mountains range of the Rocky Mountains of North America. The 12,168-foot (3,709 m) peak is in Gunnison National Forest, 2.1 miles (3.4 km) northeast by east of the Town of Crested Butte in Gunnison County, Colorado, United States. Ski lifts and runs of the Crested Butte Mountain Resort occupy the north side of the mountain.
The La Garita Mountains are a high mountain range in the San Juan Mountains, a sub-range of the Southern Rocky Mountains. The mountains are located in Saguache and Mineral counties in southwestern Colorado and are almost entirely managed as public land within the Rio Grande National Forest.
Needle Rock Natural Area is located at the western edge of the West Elk Mountains of Colorado. The surrounding terrain is characterized by laccolithic mountains flanked by precipitous cliffs, extensive talus aprons, forested mesas, canyons, and spacious, well-watered intermontane basins. Needle Rock is an intrusive plug of monzonite porphyry cropping out 3.5 miles (5.6 km) east-northeast of the Town of Crawford in Delta County, Colorado, United States. With an elevation of 7,797 feet (2,377 m), the towering rock spire stands 800 feet (240 m) tall above the floor of the Smith Fork of the Gunnison River valley. The massive rock feature originated in the Oligocene geological epoch when magma intruded between existing sedimentary rocks as the crown of a buried laccolith or possibly the underlying conduit of a laccolith. Subsequent erosion has exposed the prominent rock formation seen in the natural area today.
Tomichi Dome rises north of U.S. Highway 50 west of Hot Springs Creek and south of Waunita Hot Springs Reservoir in the southeast quarter of Gunnison County, Colorado. It is situated within the Gunnison National Forest.
West Elk Peak, elevation 13,042 ft (3,975 m), is the highest summit in the West Elk Mountains of Gunnison County, Colorado. The mountain is in the West Elk Wilderness, northwest of Gunnison. The terrain consists mostly of volcanic breccia, known in this area as West Elk Breccia, dated at 35 to 30 million years old.
East Beckwith Mountain is a prominent mountain summit in the West Elk Mountains range of the Rocky Mountains of North America. The 12,441-foot (3,792 m) peak is located in the West Elk Wilderness of Gunnison National Forest, 13.4 miles (21.5 km) west by south of the Town of Crested Butte in Gunnison County, Colorado, United States.
Whetstone Mountain, elevation 12,527 ft (3,818 m), is a summit in the Gunnison National Forest of western Colorado. The mountain is located 3 mi (4.8 km) south of Crested Butte in Gunnison County. Whetstone Mountain is one of several prominent laccoliths found in the West Elk Mountains.
Carbon Peak, elevation 12,088 ft (3,684 m), is a summit in the West Elk Mountains of Colorado. The peak is southwest of Crested Butte in the Gunnison National Forest. Carbon Peak is one of several prominent laccoliths found in the West Elk Mountains.
The geology of Utah, in the western United States, includes rocks formed at the edge of the proto-North American continent during the Precambrian. A shallow marine sedimentary environment covered the region for much of the Paleozoic and Mesozoic, followed by dryland conditions, volcanism, and the formation of the basin and range terrain in the Cenozoic.
The bedrock under the U.S. State of Colorado was assembled from island arcs accreted onto the edge of the ancient Wyoming Craton. The Sonoma orogeny uplifted the ancestral Rocky Mountains in parallel with the diversification of multicellular life. Shallow seas covered the regions, followed by the uplift current Rocky Mountains and intense volcanic activity. Colorado has thick sedimentary sequences with oil, gas and coal deposits, as well as base metals and other minerals.
The geology of Nevada began to form in the Proterozoic at the western margin of North America. Terranes accreted to the continent as a marine environment dominated the area through the Paleozoic and Mesozoic periods. Intense volcanism, the horst and graben landscape of the Basin and Range Province originating from the Farallon Plate, and both glaciers and valley lakes have played important roles in the region throughout the past 66 million years.
West Beckwith Mountain is a prominent mountain summit in the West Elk Mountains range of the Rocky Mountains of North America. The 12,185-foot (3,714 m) peak is located in the West Elk Wilderness of Gunnison National Forest, about 16.5 miles (26.5 km) southwest of Crested Butte in Gunnison County, Colorado, United States.
Youngs Peak is a small mountain located on the western side of the West Elk Mountains just east of and overlooking Crawford, Colorado. It has an elevation of 7,424 ft (2,263 m) with about 600 ft (180 m) of vertical relief above the town below. Although much of the mountain is covered with sedimentary rocks, Saddle Mountain is an exposed igneous intrusion that geologists call a laccolith.
The Anthracite Range is a mountain range in the West Elk Mountains, a sub-range of the Rocky Mountains of North America. The range is located in Gunnison County of western Colorado and lies within the West Elk Wilderness of the Gunnison National Forest. The Anthracite Range is one of several prominent laccoliths found in the West Elk Mountains.
