Tag Archives: geology

12-01-19 – Glen Canyon National Recreation Area

Glen Canyon National Recreation Area (shortened to Glen Canyon NRA or GCNRA) is a recreation and conservation unit of the United States National Park Service that encompasses the area around Lake Powell and lower Cataract Canyon in Utah and Arizona, covering 1,254,429 acres (5,076.49 km2) of mostly rugged high desert terrain. The recreation area is named for Glen Canyon, which was flooded by the Glen Canyon Dam, completed in 1966, and is now mostly submerged beneath the waters of Lake Powell.

Glen Canyon NRA borders Capitol Reef National Park and Canyonlands National Park on the north, Grand Staircase-Escalante National Monument on the west, Vermilion Cliffs National Monument and the northeasternmost reaches of Grand Canyon National Park on the southwest, and the Navajo Nation on the southeast. The southwestern end of Glen Canyon NRA in Arizona can be accessed via U.S. Route 89 and State Route 98. State Route 95 and State Route 276 lead to the northeastern end of the recreation area in Utah.

Glen Canyon NRA was established in 1972 “to provide for public use and enjoyment and to preserve the area’s scientific, historic, and scenic features.” The stated purpose of Glen Canyon NRA is for recreation as well as preservation (whereas a national park may carry more emphasis on natural preservation). As such, the area has been developed for access to Lake Powell via five marinas, four public campgrounds, two small airports, and numerous houseboat rental concessions.

The geology of the area is dominated by the Glen Canyon Group, consisting of the Navajo Sandstone, Kayenta Formation, and Wingate Sandstone. The entire stratigraphic section includes rocks dating from the Cretaceous to Pennsylvanian periods.

Source: Wikipedia
https://en.wikipedia.org/wiki/Glen_Canyon_National_Recreation_Area

11-30-19 – Rainbow Bridge National Monument


Rainbow Bridge is made from sandstone originally deposited by wind as sand dunes, during the end of the Triassic and the Jurassic periods. Extreme fluctuations in climate during the Triassic and Jurassic periods—the region was alternately a sea and desert on par with the Sahara—produced layers of sandstone with different levels of hardness. By the end of the Jurassic, the sea returned to cover these layers of sandstone and compressed them so tightly that they would persist until the present day.

As Bridge Creek flowed toward the growing Colorado River during the last ice age, it carved first through softer rocks and veered away from the harder Triassic and Jurassic sandstones, eventually creating a wide hairpin bend that flowed around a solid “fin” of sandstone that would become Rainbow Bridge. The previous course of the creek is still visible above the bridge. Water flows back on itself at bends and wide spots, creating swirling eddies along the banks. As the creek flowed around Rainbow Bridge fin, these abrasive eddies formed on both the upstream and downstream sides and cut circular alcoves in the rock wall. The sediment in the creek eventually scoured the softer layers of sandstone away, leaving the harder layers behind.

Source: Wikipedia
https://en.wikipedia.org/wiki/Rainbow_Bridge_National_Monument

11-29-19 – Valley of the Gods


The Valley of the Gods is a scenic sandstone valley near Mexican Hat in San Juan County, southeastern Utah, United States. Formerly part of Bears Ears National Monument, Valley of the Gods is located north of Monument Valley across the San Juan River and has rock formations similar to those in Monument Valley with tall, reddish brown mesas, buttes, towers and mushroom rocks—remnants of an ancient landscape.

The Valley of the Gods may be toured via a 17-mile (27 km) gravel road (San Juan County Road 242) that winds around the formations. The road is rather steep and bumpy in parts but is passable by non-four-wheel drive vehicles in dry weather. The western end joins Utah State Route 261 shortly before its 1,200-foot (370 m) ascent up Cedar Mesa at Moki Dugway, while the eastern end starts nine miles (14 km) from the town of Mexican Hat along U.S. Route 163 and heads north, initially crossing flat, open land and following the course of Lime Creek, a seasonal wash, before turning west toward the buttes and pinnacles. In addition to the gravel road, the area is also crisscrossed by off-road dirt trails.

The valley has been used as the backdrop for western movies, commercials and television shows including two episodes of the BBC science fiction show Doctor Who: “The Impossible Astronaut” and “Day of the Moon”, the second of which includes an explicit on-screen reference to the filming location. The 1984-1987 CBS TV show Airwolf is often mistakenly identified as being filmed in Valley of the Gods due to an in-episode mention but was filmed in Monument Valley

Source: Wikipedia
https://en.wikipedia.org/wiki/Valley_of_the_Gods

11-28-19 – Grand Staircase Escalante


The monument stretches from the towns of Big Water, Glendale, and Kanab, Utah in the southwest, to the towns of Escalante and Boulder in the northeast. Originally encompassing 1,880,461 acres (7,610 km2), the monument was slightly larger in area than the state of Delaware. After a reduction ordered by presidential proclamation in December 2017, the monument now encompasses 1,003,863 acres (4,062 km2).

The western part of the monument is dominated by the Paunsaugunt Plateau and the Paria River, and is adjacent to Bryce Canyon National Park. This section shows the geologic progression of the Grand Staircase. Features include the slot canyons of Bull Valley Gorge, Willis Creek, and Lick Wash which are accessed from Skutumpah Road.

The center section is dominated by a single long ridge, called the Kaiparowits Plateau from the west, and Fifty-Mile Mountain when viewed from the east. Fifty-Mile Mountain stretches southeast from the town of Escalante to the Colorado River in Glen Canyon. The eastern face of the mountain is a 2,200 ft (670 m) escarpment. The western side (the Kaiparowits Plateau) is a shallow slope descending to the south and west.

East of Fifty-Mile Mountain are the Canyons of the Escalante. The monument is bounded by Glen Canyon National Recreation Area on the east and south. The popular hiking, backpacking and canyoneering areas include Calf Creek Falls off Utah Scenic Byway 12, and Zebra Canyon, Harris Wash, and the Devils Garden. The latter areas are accessed via the Hole-in-the-Rock Road which extends southeast from Escalante, near the base of Fifty-Mile Mountain. The Dry Fork Slots of Coyote Gulch and lower Coyote Gulch are also located off the Hole-in-the-Rock Road.

Source: Wikipedia

11-24-19 – Sand to Snow and Joshua Tree


I went for a wander intending to visit Sand To Snow National Monument, but found myself in a hike-in only situation controlled by The Wildlands Conservancy, and I wasn’t geared for a long hike that day, so I spent some time in The Wildlands Conservancy before setting off to the far more accessible Joshua Tree National Park.

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Sand to Snow National Monument is a U.S. National Monument located in San Bernardino County and into northern Riverside County, Southern California. It protects diverse montane and desert habitats of the San Bernardino Mountains, southern Mojave Desert, and northwestern Colorado Desert. The national monument protects a total of 154,000 acres (62,000 ha), with the Bureau of Land Management (BLM) managing 83,000 acres (34,000 ha) acres, and the USFS−San Bernardino National Forest managing 71,000 acres (29,000 ha). It extends from around 1,000 feet (300 m) on the Coachella Valley desert floor up to over 11,000 feet (3,400 m) in the San Bernardino Mountains. Over 100,000 acres (40,000 ha) of the national monument are within the San Gorgonio Wilderness area, which was designated by Congress in 1964. An eastern border in the Little San Bernardino Mountains abuts Joshua Tree National Park. A separate section expands the Bighorn Mountain Wilderness area to the northeast. 30 miles (48 km) of the Pacific Crest National Scenic Trail pass through the monument. The headwaters of the Santa Ana River, Whitewater River, Morongo Creek, and San Gorgonio River are within it. The park protects a significant wildlife corridor and landscape linkage between the San Bernardino National Forest/San Gorgonio Wilderness area, Joshua Tree National Park, and Bighorn Mountain Wilderness area.

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Joshua Tree National Park is an American national park in southeastern California, east of Los Angeles and San Bernardino, near Palm Springs. The park is named for the Joshua trees (Yucca brevifolia) native to the Mojave Desert. Originally declared a national monument in 1936, Joshua Tree was redesignated as a national park in 1994 when the U.S. Congress passed the California Desert Protection Act. Encompassing a total of 790,636 acres (1,235.4 sq mi; 3,199.6 km2)—an area slightly larger than the state of Rhode Island—the park includes 429,690 acres (671.4 sq mi; 1,738.9 km2) of designated wilderness. Straddling the border between San Bernardino County and Riverside County, the park includes parts of two deserts, each an ecosystem whose characteristics are determined primarily by elevation: the higher Mojave Desert and the lower Colorado Desert. The Little San Bernardino Mountains traverse the southwest edge of the park.

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Source: Wikipedia

09-17-19 – Timpanagos Cave National Monument


Timpanogos Cave National Monument is a United States National Monument protecting the Timpanogos Cave Historic District and a cave system on Mount Timpanogos in the Wasatch Mountains in American Fork Canyon near American Fork, Utah, in the United States. The site is managed by the National Park Service. The 1.5-mile (2.4 km) trail to the cave is steep, gaining close to 1,000 feet (300 m), but paved and fairly wide, making the caves accessible to most. The three caves of the system, one of which is specifically called Timpanogos Cave, are only viewable on guided tours when the monument is open, usually from May through September depending on snow conditions and funding. There is the standard tour going through the cave system, and an Introduction to Caving tour which teaches Leave No Trace caving and goes further into Hansen Cave.

The three caves of the Monument that are tourable are: Hansen Cave, Middle Cave, and Timpanogos Cave. The three caves are connected by manmade tunnels blasted in the 1930s by the Works Progress Administration . The average temperature in the caves is 46 degrees Fahrenheit. Many colorful cave features or speleothems can be seen. Among the most interesting are the helictites, which are hollowed, twisted, spiraling straws of deposited calcite or aragonite. They are formed when water travels through the tube and then evaporates, leaving a trace mineral deposit at the end. Other speleothems found in the cave include: cave bacon, cave columns, flowstone, cave popcorn, cave drapery, stalactites and stalagmites.

09-14-19 – Craters of the Moon National Monument


Craters of the Moon National Monument and Preserve is a U.S. National Monument and national preserve in the Snake River Plain in central Idaho. It is along US 20 (concurrent with US 93 and US 26), between the small towns of Arco and Carey, at an average elevation of 5,900 feet (1,800 m) above sea level. The protected area’s features are volcanic and represent one of the best-preserved flood basalt areas in the continental United States.

The Monument was established on May 2, 1924. In November 2000, a presidential proclamation by President Clinton greatly expanded the Monument area. The National Park Service portions of the expanded Monument were designated as Craters of the Moon National Preserve in August 2002. It lies in parts of Blaine, Butte, Lincoln, Minidoka, and Power counties. The area is managed cooperatively by the National Park Service and the Bureau of Land Management (BLM).

The Monument and Preserve encompass three major lava fields and about 400 square miles (1,000 km2) of sagebrush steppe grasslands to cover a total area of 1,117 square miles (2,893 km2). The Monument alone covers 53,571 acres (21,679 ha). All three lava fields lie along the Great Rift of Idaho, with some of the best examples of open rift cracks in the world, including the deepest known on Earth at 800 feet (240 m). There are excellent examples of almost every variety of basaltic lava, as well as tree molds (cavities left by lava-incinerated trees), lava tubes (a type of cave), and many other volcanic features


09-13-19 – City Of Rocks National Preserve



The City of Rocks National Reserve, also known as the Silent City of Rocks, is a United States National Reserve and state park lying 2 miles (3.2 km) north of the south central Idaho border with Utah. It is widely known for its excellent rock climbing and rock formations.

The rock spires in the City of Rocks and adjacent Castle Rocks State Park are largely composed of granitic rock of the Oligocene Almo pluton and Archean Green Creek Complex.

California Trail wagon trains of the 1840s and 1850s left the Raft River valley and traveled through the area and over Granite Pass into Nevada. Names or initials of emigrants written in axle grease are still visible on Register Rock. Ruts from wagon wheels also can be seen in some of the rocks.

The landscape of City of Rocks has been sculpted from granite that was intruded into the crust during two widely spaced times. The granite that composes most of the spires is part of the 28-million-year-old Almo pluton. However, some of the spires are made of granite that is part of the 2.5 billion-year-old Green Creek Complex that contains some of the oldest rocks in the western United States. The granite has eroded into a fascinating assortment of shapes.

City of Rocks was designated a National Reserve, a unit of the National Park Service, in recognition of the nationally significant geological and scenic values of its rock formations and the historical significance of the California Trail. Rock formations in the reserve developed through an erosion process called exfoliation, during which thin rock plates and scales sloughed off along joints in the rocks. The joints, or fractures, resulted from the contraction of the granite as it cooled, from an upward expansion of the granite as overlying materials were eroded away, and from regional tectonic stresses. The granite has eroded into a fascinating assortment of shapes as high as 600 feet (180 m). The upper surfaces of many of the rocks are covered with flat-floored weathering pits known as panholes. The most notable panhole is located on top of Bath Rock and is continuously filled with water from rain or snowmelt.

Source: Wikipedia

09-13-19 – Basin and Range National Monument


Basin and Range National Monument is a national monument of the United States spanning approximately 704,000 acres (1,100 sq mi; 2,800 km2) of remote, undeveloped mountains and valleys in Lincoln and Nye counties in southeastern Nevada. It is described as “one of the emptiest spaces in a state famous for its emptiness.”

The Basin and Range National Monument area has geological, ecological, cultural, historical, paleoecological, seismological, archaeological, and paleoclimatological significance. The area is located in a transitional region between the Mojave Desert and the Sagebrush Steppe of the Great Basin.

Major features within the national monument include: Garden Valley and Coal Valley; the Worthington Mountains, containing the Worthington Mountains Wilderness Area; the Golden Gate Range; the Seaman Range; the Mount Irish Range; the Hiko Narrows; the White River Narrows; and the Shooting Gallery rock art site. Native American rock art at the site is about 4,000 years old.

Fauna of significance in the national monument include desert bighorn sheep, golden eagle, and many species of bat, lizard, and snake.

Source: Wikipedia

08-18-19 – Mono-Inyo Craters


The Mono–Inyo Craters are a volcanic chain of craters, domes and lava flows in Mono County, Eastern California. The chain stretches 25 miles (40 km) from the northwest shore of Mono Lake to the south of Mammoth Mountain. The Mono Lake Volcanic Field forms the northernmost part of the chain and consists of two volcanic islands in the lake and one cinder cone volcano on its northwest shore. Most of the Mono Craters, which make up the bulk of the northern part of the Mono–Inyo chain, are phreatic (steam explosion) volcanoes that have since been either plugged or over-topped by rhyolite domes and lava flows. The Inyo Craters form much of the southern part of the chain and consist of phreatic explosion pits, and rhyolitic lava flows and domes. The southernmost part of the chain consists of fumaroles and explosion pits on Mammoth Mountain and a set of cinder cones south of the mountain; the latter are called the Red Cones.

Eruptions along the narrow fissure system under the chain began in the west moat of Long Valley Caldera 400,000 to 60,000 years ago. Mammoth Mountain was formed during this period. Multiple eruptions from 40,000 to 600 years ago created the Mono Craters and eruptions 5,000 to 500 years ago formed the Inyo Craters. Lava flows 5,000 years ago built the Red Cones, and explosion pits on Mammoth Mountain were excavated in the last 1,000 years. Uplift of Paoha Island in Mono Lake about 250 years ago is the most recent activity. These eruptions most likely originated from small magma bodies rather than from a single, large magma chamber like the one that produced the massive Long Valley Caldera eruption 760,000 years ago. During the past 3,000 years, eruptions have occurred every 250 to 700 years. In 1980, a series of earthquakes and uplift within and south of Long Valley Caldera indicated renewed activity in the area.

The region has been used by humans for centuries. Obsidian was collected by Mono Paiutes for making sharp tools and arrow points. Glassy rock continues to be removed in modern times for use as commercial scour and yard decoration. Mono Mills processed timber felled on or near the volcanoes for the nearby boomtown Bodie in the late 19th to early 20th centuries. Water diversions into the Los Angeles Aqueduct system from their natural outlets in Mono Lake started in 1941 after a water tunnel was cut under the Mono Craters. Mono Lake Volcanic Field and a large part of the Mono Craters gained some protection under Mono Basin National Forest Scenic Area in 1984. Resource use along all of the chain is managed by the United States Forest Service as part of Inyo National Forest. Various activities are possible along the chain, including hiking, bird watching, canoeing, skiing, and mountain biking.

Source: Wikipedia