Glen Canyon is a natural canyon in southeastern and south-central Utah. A small part of the lower end of Glen Canyon extends into the northern part of Arizona and terminates at the Vermilion Cliffs area in the United States. Like the Grand Canyon to the south, Glen Canyon is part of the immense system of canyons carved by the Colorado River and its tributaries. In 1963, a reservoir, Lake Powell, was created by the construction of the Glen Canyon Dam, in the Arizona portion of Glen Canyon; this dam backed water into Utah. Lake Powell was not the result of negotiations over the controversial damming of the Green River within Dinosaur National Monument at Echo Park; the Echo Park Dam proposal was abandoned due to country wide citizen pressure on Congress to do so. Glen Canyon dam remains a central issue for modern environmentalist movements. Beginning in the late 1990s, the Sierra Club and other organizations renewed the call to dismantle the dam and drain Lake Powell in Lower Glen Canyon. Today, Glen Canyon and Lake Powell are managed by the U.
S. Department of the Interior within Glen Canyon National Recreation Area. Around 1956, archaeologists and biologists from the University of Utah and the Museum of Northern Arizona, using National Park research grants, planned an emergency excavation of Lower Glen Canyon, soon to be flooded by the new Glen Canyon Dam. Between 1958 and 1960, four investigative phases, combined with other surveys prior to 1957, discovered 250 archaeological sites within the canyon; the Lower Glen Canyon survey was completed in 1958. Excavations began during the summer of 1958 on 16 sites. A thesis emerged that prehistoric people living permanently on the highlands south of Glen Canyon, on the Cummings Mesa, farmed the Lower Glen Canyon on a seasonal basis, gathered raw materials. To prove this thesis of seasonal habitation, criteria such as architectural units, locations of trail systems, occurrence of ceremonial structures, prevalence of burials, position of natural and cultural strata. Four types of sites are described in the survey classified as either open sites situated on rock terraces.
Open sites are the majority on both sides of the river. The majority of sites Navajo camps, feature lithic garbage or ceramics, or both. Talus sites are recorded. Most of the cultural remains found are chipped stone tools, including projectile points, drills, knives and ground stone tools and manos; the collection of sherds are Tusayan Gray Ware and Tusayan White Ware. Petroglyph panels are found throughout Glen Canyon. "Pecked and incised figures depict mountain sheep, human figures, human handprints and animal tracks. Geometric figures range from circles and spirals to complex rectilinear patterns; the human figures have triangular bodies. Painted figures have been reported for both sides of the river.... Petroglyph panels of such quality are lacking from the highland regions adjacent to Glen Canyon". Studies indicate a chronology for the Lower Glen Canyon prehistory, "from pre-A. D. 1 to the 15th century and recorded history from 1776 to the present". A Late Basketmaker II Era is represented by several sites.
Radiocarbon dates from charcoal material are from A. D. 250 to 440. Basketmaker III is not found in the Lower Glen Canyon, but is documented in Navajo Canyon, a large left bank tributary of the Colorado River, within the geographical area of the Lower Glen Canyon. Basketmaker III introduces fired pottery Lino Black-on-gray and Lino Gray, some small amounts of Lino Fugitive Red and Obelisk Gray; the Basketmaker culture is believed to have lasted than Pueblo I. Pueblo I Era remains are found at Rock Creek in Lower Glen Canyon, in Navajo Canyon; the pottery types are Kana-a Black-on-white, Deadmans Black-on-red, Kana-a Gray, made from deposits found in Lizard Alcove. Pueblo I is the best documented period of Navajo Canyon, beginning in 800 A. D, lasting 200 years. "Pueblo II in Navajo Canyon is represented by the absence of Kana-a Black-on-white and the dominance of Black Mesa Black-on-white". Pueblo II and early Pueblo III is the best documented cultural area in Lower Glen Canyon corresponding with habitation on Cummings Mesa.
Pottery includes Tusayan varieties, Black-on-white, Black-on-red, Red Wear Polychromes. Hopi people from the Jeddito area came into the canyons in the 14th century, represented by Yellow Wares Jeddito Black-on-yellow, Jeddito plain. Most of the ceramic material found in the main canyon was made in the highlands, although it is possible some pottery was manufactured in Lower Glen Canyon. Clay deposits are found along the river, some crude pottery specimens, that may have been made there. Only four burials were found in Lower Glen Canyon at three sites. Trash dumps are not common at most sites; this is more evidence to suggest the seasonal occupation of farmers. Cultural similarities are based on the absence, of certain types of ceramic wares. Group types of pottery including Kayenta, with Fremont, Mesa Verde or Anasazi types of White and Desert Gray Ware were found on the right bank of the Colorado. Basketmaker II is characterized by a lack of pottery, as well as above ground and underground cists lined with slabs.
There is little evidence of permanent occupation except at Talus Ruin, a small pueblo with a kiva, a
Glenwood Canyon is a rugged scenic 12.5 mi canyon on the Colorado River in western Colorado in the United States. Its walls climb as high as 1,300 feet above the Colorado River, it is the largest such canyon on the Upper Colorado. The canyon, which has provided the routes of railroads and highways through western Colorado furnishes the routes of Interstate 70 and the Central Corridor between Denver and Grand Junction; the canyon stretches from near Dotsero, where the Colorado receives the Eagle River, downstream in a west-southwest direction to just east of Glenwood Springs, on the mouth of the Roaring Fork. Most of the canyon is with the upper portion near Dotsero lying in Eagle County. In 1906, the canyon provided the route of the Taylor State Road, a gravel road, the first route for automobiles through the Colorado Rockies; the canyon provided the route for the Denver and Rio Grande Western Railroad in the late 19th century. Through acquisitions, the line is part of the Union Pacific system.
As Glenwood Canyon was one of the iconic scenic views along the California Zephyr passenger train, a monument to the dome car design was installed in the canyon. In the 1990s, the monument was relocated to the Colorado Railroad Museum in Golden to make way for the construction on Interstate 70; the canyon is considered one of the most scenic natural features on the Interstate Highway System of the United States. Foot access to the canyon is available at four rest areas along Interstate 70 in the canyon; the Hanging Lake Rest Area provides access to the canyon along a stretch where I-70 is concealed in the Hanging Lake Tunnel. The freeway is prone to rockslides in the canyon, such as the one that closed it in February 2016; the canyon was formed recently in Pleistocene time by the rapid cutting of the Colorado down through layers of sedimentary rock. The upper layers of the canyon are sandstone from Mississippian. Sections of the lower canyon walls are made of Cambrian rock; the Mississippian layer, prominent throughout much of the upper rim sections of the canyon is part of the Leadville Formation.
Gore Canyon Roadside Geology of Colorado by Halka Chronic. Glenwood Canyon I70 motorway project 12 years later
Canyonlands National Park
Canyonlands National Park is an American national park located in southeastern Utah near the town of Moab. The park preserves a colorful landscape eroded into countless canyons and buttes by the Colorado River, the Green River, their respective tributaries. Legislation creating the park was signed into law by President Lyndon Johnson on September 12, 1964; the park is divided into four districts: the Island in the Sky, the Needles, the Maze, the combined rivers—the Green and Colorado—which carved two large canyons into the Colorado Plateau. While these areas share a primitive desert atmosphere, each retains its own character. Author Edward Abbey, a frequent visitor, described the Canyonlands as "the most weird, magical place on earth—there is nothing else like it anywhere." In the early 1950s, Bates Wilson superintendent of Arches National Monument, began exploring the area to the south and west of Moab, Utah. After seeing what is now known as the Needles District of Canyonlands National Park, Wilson began advocating for the establishment of a new national park that would include the Needles.
Additional explorations by Wilson and others expanded the areas proposed for inclusion into the new national park to include the confluence of Green and Colorado rivers, the Maze District, Horseshoe Canyon. In 1961, Secretary of the Interior Stewart Udall was scheduled to address a conference at Grand Canyon National Park. On his flight to the conference, he flew over the Confluence; the view sparked Udall's interest in Wilson's proposal for a new national park in that area and Udall began promoting the establishment of Canyonlands National Park. In September 1964, after several years of debate, President Lyndon B. Johnson signed Pub. L. 88–590, which established Canyonlands National Park as a new national park. Bates Wilson became the first superintendent of the new park, he is referred to as the "Father of Canyonlands." Canyonlands is a popular recreational destination. Since 2007, more than 400,000 people have visited the park each year with a record of 776,218 visitors in 2016, representing a 22 percent increase from the prior year.
The geography of the park is well suited to a number of different recreational uses. Hikers, mountain bikers and four-wheelers all enjoy traveling the rugged, remote trails within the Park; the White Rim Road traverses the White Rim Sandstone level of the park between the rivers and the Island in the Sky. Since 2015, day-use permits must be obtained before travelling on the White Rim Road due to the increasing popularity of driving and bicycling along it; the park service's intent is to provide a better wilderness experience for all visitors while minimizing impacts on the natural surroundings. As of 2016, the Island in the Sky district, with its proximity to the Moab, Utah area, attracts 76.7 percent of total park visitors. The Needles district is the second most; the remote Maze district accounts for only about 1.5 percent of visitors, while river rafters and other river users account for the remaining 1.1 percent of total park visitation. Rafters and kayakers float the calm stretches of the Green River and Colorado River above the Confluence.
Below the Confluence, Cataract Canyon contains powerful whitewater rapids, similar to those found in the Grand Canyon. However, since there is no large impoundment on the Colorado River above Canyonlands National Park, river flow through the Confluence is determined by snowmelt, not management; as a result, in combination with Cataract Canyon's unique graben geology, this stretch of river offers the largest whitewater in North America in heavy snow years. Political compromise at the time of the park's creation limited the protected area to an arbitrary portion of the Canyonlands basin. Conservationists hope to complete the park by bringing the boundaries up to the high sandstone rims that form the natural border of the Canyonlands landscape; the Colorado River and Green River combine within the park dividing it into three districts called the Island in the Sky, the Needles and the Maze. The Colorado River flows through Cataract Canyon below its confluence with the Green River; the Island in the Sky district is a broad and level mesa to the north of the park between Colorado and Green river with many overlooks from the White Rim, a sandstone bench 1,200 feet below the Island, the rivers, which are another 1,000 feet below the White Rim.
The Needles district is located east of the Colorado River and is named after the red and white banded rock pinnacles which dominate it, but various other forms of sculptured rock such as canyons, potholes, a number of arches similar to the ones of the nearby Arches National Park can be found as well. Unlike Arches National Park, where many arches are accessible by short to moderate hikes or by car, most of the arches in the Needles district lie in back country canyons and require long hikes or four-wheel-drive trips to reach them; the area was once home of the Ancestral Puebloans. Although the items and tools they used have been taken away by looters, some of their stone and mud dwellings are well-preserved; the Ancestral Puebloans left traces in the form of petroglyphs, most notably on the so-called Newspaper Rock near the Visitor Center at the entrance of this district. The Maze district is located west of the Colorado and Green rivers, is the least accessible section of the park, one of the most remote and inaccessible areas of the United States.
A geographically detached section of the park located west-northwest of the main unit, Horseshoe Canyon Unit, contains panels of rock art made by hunter-gatherers from the Late Archaic Pe
The Precambrian is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic eon, named after Cambria, the Latinised name for Wales, where rocks from this age were first studied; the Precambrian accounts for 88% of the Earth's geologic time. The Precambrian is an informal unit of geologic time, subdivided into three eons of the geologic time scale, it spans from the formation of Earth about 4.6 billion years ago to the beginning of the Cambrian Period, about 541 million years ago, when hard-shelled creatures first appeared in abundance. Little is known about the Precambrian, despite it making up seven-eighths of the Earth's history, what is known has been discovered from the 1960s onwards; the Precambrian fossil record is poorer than that of the succeeding Phanerozoic, fossils from the Precambrian are of limited biostratigraphic use. This is because many Precambrian rocks have been metamorphosed, obscuring their origins, while others have been destroyed by erosion, or remain buried beneath Phanerozoic strata.
It is thought that the Earth coalesced from material in orbit around the Sun at 4,543 Ma, may have been struck by a large planetesimal shortly after it formed, splitting off material that formed the Moon. A stable crust was in place by 4,433 Ma, since zircon crystals from Western Australia have been dated at 4,404 ± 8 Ma; the term "Precambrian" is recognized by the International Commission on Stratigraphy as the only "supereon" in geologic time. "Precambrian" is still used by geologists and paleontologists for general discussions not requiring the more specific eon names. As of 2010, the United States Geological Survey considers the term informal, lacking a stratigraphic rank. A specific date for the origin of life has not been determined. Carbon found in 3.8 billion-year-old rocks from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have been found in Western Australia. Probable fossils 100 million years older have been found in the same area.
However, there is evidence. There is a solid record of bacterial life throughout the remainder of the Precambrian. Excluding a few contested reports of much older forms from North America and India, the first complex multicellular life forms seem to have appeared at 1500 Ma, in the Mesoproterozoic era of the Proterozoic eon. Fossil evidence from the Ediacaran period of such complex life comes from the Lantian formation, at least 580 million years ago. A diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma; these are referred to as Vendian biota. Hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic eon. By the middle of the following Cambrian period, a diverse fauna is recorded in the Burgess Shale, including some which may represent stem groups of modern taxa; the increase in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life. While land seems to have been devoid of plants and animals and other microbes formed prokaryotic mats that covered terrestrial areas.
Tracks from an animal with leg like appendages have been found in what was mud 551 million years ago. Evidence of the details of plate motions and other tectonic activity in the Precambrian has been poorly preserved, it is believed that small proto-continents existed prior to 4280 Ma, that most of the Earth's landmasses collected into a single supercontinent around 1130 Ma. The supercontinent, known as Rodinia, broke up around 750 Ma. A number of glacial periods have been identified going as far back as the Huronian epoch 2400–2100 Ma. One of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a "Snowball Earth"; the atmosphere of the early Earth is not well understood. Most geologists believe it was composed of nitrogen, carbon dioxide, other inert gases, was lacking in free oxygen. There is, evidence that an oxygen-rich atmosphere existed since the early Archean. At present, it is still believed that molecular oxygen was not a significant fraction of Earth's atmosphere until after photosynthetic life forms evolved and began to produce it in large quantities as a byproduct of their metabolism.
This radical shift from a chemically inert to an oxidizing atmosphere caused an ecological crisis, sometimes called the oxygen catastrophe. At first, oxygen would have combined with other elements in Earth's crust iron, removing it from the atmosphere. After the supply of oxidizable surfaces ran out, oxygen would have begun to accumulate in the atmosphere, the modern high-oxygen atmosphere would have developed. Evidence for this lies in older rocks that contain massive banded iron formations that were laid down as iron oxides. A terminology has evolved covering the early years of the Earth's existence, as radiometric dating has allowed real dates to be assigned to specific formations and features; the Precambrian is divided into
Marble Canyon is the section of the Colorado River canyon in northern Arizona from Lee's Ferry to the confluence with the Little Colorado River, which marks the beginning of the Grand Canyon. Lee's Ferry is a common launching point for river runners starting their journey through the Grand Canyon. Marble Canyon is well known for the Navajo Bridge, where US Highway 89A crosses the Colorado River. Marble Canyon marks the western boundary of the Navajo Nation. In 1975, the former Marble Canyon National Monument, which followed the Colorado River northeast from the Grand Canyon to Lee's Ferry, was made part of Grand Canyon National Park; the name Marble Canyon is a misnomer. Although John Wesley Powell knew this when he named the canyon, he thought the polished limestone looked like marble. In his words, "The limestone of the canyon is polished, makes a beautiful marble. Sometimes the rocks are of many colors - white, gray and purple, with saffron tints." Marble Canyon is the site of one of the last great proposed dam projects on the Colorado, the Marble Canyon Dam.
Proposed and investigated in the early 1950s by the United States Bureau of Reclamation, the proposal met substantial opposition, notably from the Sierra Club, when a revived proposal was considered by the state of Arizona as part of the Central Arizona Project from 1965 to 1968. The proposed dam was abandoned in 1968. Exploratory holes, which were drilled in the Redwall Limestone of the canyon walls in an early phase of the abortive project, can still be seen at Mile 39.2. Marble Canyon is the only home of the endangered cactus Pediocactus bradyi
The Grand Canyon is a steep-sided canyon carved by the Colorado River in Arizona, United States. The Grand Canyon is 277 miles long, up to 18 miles wide and attains a depth of over a mile; the canyon and adjacent rim are contained within Grand Canyon National Park, the Kaibab National Forest, Grand Canyon-Parashant National Monument, the Hualapai Indian Reservation, the Havasupai Indian Reservation and the Navajo Nation. President Theodore Roosevelt was a major proponent of preservation of the Grand Canyon area, visited it on numerous occasions to hunt and enjoy the scenery. Nearly two billion years of Earth's geological history have been exposed as the Colorado River and its tributaries cut their channels through layer after layer of rock while the Colorado Plateau was uplifted. While some aspects about the history of incision of the canyon are debated by geologists, several recent studies support the hypothesis that the Colorado River established its course through the area about 5 to 6 million years ago.
Since that time, the Colorado River has driven the down-cutting of the tributaries and retreat of the cliffs deepening and widening the canyon. For thousands of years, the area has been continuously inhabited by Native Americans, who built settlements within the canyon and its many caves; the Pueblo people considered the Grand Canyon a holy site, made pilgrimages to it. The first European known to have viewed the Grand Canyon was García López de Cárdenas from Spain, who arrived in 1540; the Grand Canyon is a river valley in the Colorado Plateau that exposes uplifted Proterozoic and Paleozoic strata, is one of the six distinct physiographic sections of the Colorado Plateau province. It is not the deepest canyon in the world. However, the Grand Canyon is known for its visually overwhelming size and its intricate and colorful landscape. Geologically, it is significant because of the thick sequence of ancient rocks that are well preserved and exposed in the walls of the canyon; these rock layers record much of the early geologic history of the North American continent.
Uplift associated with mountain formation moved these sediments thousands of feet upward and created the Colorado Plateau. The higher elevation has resulted in greater precipitation in the Colorado River drainage area, but not enough to change the Grand Canyon area from being semi-arid; the uplift of the Colorado Plateau is uneven, the Kaibab Plateau that Grand Canyon bisects is over one thousand feet higher at the North Rim than at the South Rim. All runoff from the North Rim flows toward the Grand Canyon, while much of the runoff on the plateau behind the South Rim flows away from the canyon; the result is deeper and longer tributary washes and canyons on the north side and shorter and steeper side canyons on the south side. Temperatures on the North Rim are lower than those on the South Rim because of the greater elevation. Heavy rains are common on both rims during the summer months. Access to the North Rim via the primary route leading to the canyon is limited during the winter season due to road closures.
The Grand Canyon is part of the Colorado River basin which has developed over the past 70 million years, in part based on apatite /He thermochronometry showing that Grand Canyon reached a depth near to the modern depth by 20 Ma. A recent study examining caves near Grand Canyon places their origins beginning about 17 million years ago. Previous estimates had placed the age of the canyon at 5–6 million years; the study, published in the journal Science in 2008, used uranium-lead dating to analyze calcite deposits found on the walls of nine caves throughout the canyon. There is a substantial amount of controversy because this research suggests such a substantial departure from prior supported scientific consensus. In December 2012, a study published in the journal Science claimed new tests had suggested the Grand Canyon could be as old as 70 million years. However, this study has been criticized by those who support the "young canyon" age of around six million years as " attempt to push the interpretation of their new data to their limits without consideration of the whole range of other geologic data sets."The canyon is the result of erosion which exposes one of the most complete geologic columns on the planet.
The major geologic exposures in the Grand Canyon range in age from the 2-billion-year-old Vishnu Schist at the bottom of the Inner Gorge to the 230-million-year-old Kaibab Limestone on the Rim. There is a gap of about a billion years between the 500-million-year-old stratum and the level below it, which dates to about 1.5 billion years ago. This large unconformity indicates a long period. Many of the formations were deposited in warm shallow seas, near-shore environments, swamps as the seashore advanced and retreated over the edge of a proto-North America. Major exceptions include the Permian Coconino Sandstone, which contains abundant geological evidence of aeolian sand dune deposition. Several parts of the Supai Group were deposited in non–marine environments; the great depth of the Grand Canyon and the height of its strata can be attributed to 5–10 thousand feet of uplift of the Colorado Plateau, starting about 65 million years ago. This uplift has steepened the stream gradient of the Colorado River