The Grand Mesa is a large mesa in western Colorado in the United States. It is the largest flat-topped mountain in the world. 500 square miles (1,300 km2) and stretches for about 40 miles (64 km) east of Grand Junction between the Colorado River and the Gunnison River, its tributary to the south. The north side of the mesa is drained largely by Plateau Creek, a smaller tributary of the Colorado. The west side is drained largely by Kannah Creek, which is received to the west by the lower Gunnison River. The mesa rises about 6,000 feet (1,800 m) above the surrounding river valleys, including the Grand Valley to the west, reaching an elevation of about 11,000 feet (3,400 m). Much of the mesa is within Grand Mesa National Forest. Over 300 lakes, including many reservoirs created and used for drinking and irrigation water, are scattered along the top of the formation. The Grand Mesa is flat in some areas, but quite rugged in others.It has an area of about
The mesa is topped by a hard layer of volcanic basalt. This layer formed between about 10.9 and 9.6 million years ago, by the eruption of at least 27 separate lava flows from a vent in the Crag Crest area and probably other vents. This built up a maximum total thickness of more than 93 meters (310 feet) of basalt. The resistant basalt layer suppressed erosion compared to the surrounding sedimentary rock layers, which suffered rapid downcutting from the action of the Colorado and the Gunnison rivers. The top layer rests on a thick sequence of Eocene shale and sandstone known as the Green River and Wasatch Formations. These layers in turn rest on a Cretaceous layer known as the Mesaverde Group that forms a cliff about halfway up the side of the mesa. The lowest layers are yellow and gray Mancos Shale of late Cretaceous age. The shale continues outward into the surrounding valleys in the vicinity of the mesa, providing a soil base that is fertile for various kinds of agriculture, especially in the Gunnison Valley to the south.
The flows of the Grand Mesa volcanic field may have originally covered an area of 1,300 square kilometers (500 square miles), but erosion has reduced the intact flows to just 166 square kilometers (64 square miles).
Climate on Grand Mesa varies by elevation. Higher elevations tend to be cooler and receive more precipitation. The top of the mesa is more than two miles above sea level, and experiences an alpine climate with substantial amounts of precipitation throughout the year. Because of the high altitude, summer days are mild, and temperatures drop sharply after sunset. Winter temperatures rarely rise above freezing, and can be extremely cold, often falling far below zero, especially at night. The top of the mesa is usually snow-free from late June through early October; however, the mesa receives heavy snowfall in the winter, rendering the forest service roads impassable. Accumulations of 20 or 30 inches of snow in the winter are typical. Surrounding areas with lower elevation are warmer and more arid throughout the year.
The following climate data is for Mesa Lakes Resort, located on the north slopes of the mesa at 9,800 feet above sea level, which experiences a subalpine climate (Köppen Dfc).
|Climate data for Mesa Lakes Resort, Colorado (1971-1979)|
|Record high °F (°C)||47|
|Average high °F (°C)||27.9|
|Average low °F (°C)||3.4|
|Record low °F (°C)||−35|
|Average precipitation inches (mm)||2.54|
|Average snowfall inches (cm)||67.2|
|Source: The Western Regional Climate Center|
The mesa is traversed by the Grand Mesa Scenic and Historic Byway, which includes SH 65, between the town of Mesa on the north and the town of Cedaredge on the south. The route over the mesa provides a dramatic contrast in landscape, climate and vegetation. On the north side, the road climbs the steep terrain near the Powderhorn Resort ski area. The forested top of the mesa remains snowbound much later in the spring than the surrounding valleys, and is a popular location for cross-country skiing and snowmobiling.
Black Canyon of the Gunnison National Park is an American national park located in western Colorado and managed by the National Park Service. There are two primary entrances to the park: the south rim entrance is located 15 miles (24 km) east of Montrose, while the north rim entrance is 11 miles (18 km) south of Crawford and is closed in the winter. The park contains 12 miles (19 km) of the 48-mile (77 km) long Black Canyon of the Gunnison River. The national park itself contains the deepest and most dramatic section of the canyon, but the canyon continues upstream into Curecanti National Recreation Area and downstream into Gunnison Gorge National Conservation Area. The canyon's name owes itself to the fact that parts of the gorge only receive 33 minutes of sunlight a day, according to Images of America: The Black Canyon of the Gunnison. In the book, author Duane Vandenbusche states, "Several canyons of the American West are longer and some are deeper, but none combines the depth, sheerness, narrowness, darkness, and dread of the Black Canyon."
The Western Slope is the part of the state of Colorado west of the Continental Divide. Bodies of water west of the Divide flow toward the Pacific Ocean. Water that falls and flows east of the Divide heads east. The Western Slope encompasses about 33% of the state, but has just 10% of the state's residents. The eastern part of the state, including the San Luis Valley and the Front Range, is the more populous portion of the state.
The Gunnison River is located in western Colorado, and it is one of the largest tributaries of the Colorado river. The 180-mile (289-km) long river flows east to west, and it has a drainage area of 7,923 square miles (20,520 km2) according to the USGS. The drainage basin of the Gunnison River collects water from different habitats, such as forests and alpine meadows, located the along Continental Divide. As the river flows westward, it carves through the San Juan Mountains. It flows into the Colorado River at Grand Junction.
The geology of the Grand Canyon area includes one of the most complete and studied sequences of rock on Earth. The nearly 40 major sedimentary rock layers exposed in the Grand Canyon and in the Grand Canyon National Park area range in age from about 200 million to nearly 2 billion years old. Most were deposited in warm, shallow seas and near ancient, long-gone sea shores in western North America. Both marine and terrestrial sediments are represented, including lithified sand dunes from an extinct desert. There are at least 14 known unconformities in the geologic record found in the Grand Canyon.
The geology of the Zion and Kolob canyons area includes nine known exposed formations, all visible in Zion National Park in the U.S. state of Utah. Together, these formations represent about 150 million years of mostly Mesozoic-aged sedimentation in that part of North America. Part of a super-sequence of rock units called the Grand Staircase, the formations exposed in the Zion and Kolob area were deposited in several different environments that range from the warm shallow seas of the Kaibab and Moenkopi formations, streams and lakes of the Chinle, Moenave, and Kayenta formations to the large deserts of the Navajo and Temple Cap formations and dry near shore environments of the Carmel Formation.
The exposed geology of the Bryce Canyon area in Utah shows a record of deposition that covers the last part of the Cretaceous Period and the first half of the Cenozoic era in that part of North America. The ancient depositional environment of the region around what is now Bryce Canyon National Park varied from the warm shallow sea in which the Dakota Sandstone and the Tropic Shale were deposited to the cool streams and lakes that contributed sediment to the colorful Claron Formation that dominates the park's amphitheaters.
The Colorado Plateau, also known as the Colorado Plateau Province, is a physiographic and desert region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. This province 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.
Black Mesa is a mesa in the U.S. states of Colorado, New Mexico, and Oklahoma. It extends from Mesa de Maya, Colorado southeasterly 28 miles (45 km) along the north bank of the Cimarron River, crossing the northeast corner of New Mexico to end at the confluence of the Cimarron River and North Carrizo Creek near Kenton in the Oklahoma panhandle. Its highest elevation is 5,705 feet (1,739 m) in Colorado. The highest point of Black Mesa within New Mexico is 5,239 feet (1,597 m). In northwestern Cimarron County, Oklahoma, Black Mesa reaches 4,973 feet (1,516 m), the highest point in the state of Oklahoma. The plateau that formed at the top of the mesa has been known as a "geological wonder" of North America. There is abundant wildlife in this shortgrass prairie environment, including mountain lions, butterflies, and the Texas horned lizard. It is said to be the birthplace of "Mesanda Gamage" in many chess fanficiton stories as well.
The exposed geology of the Capitol Reef area presents a record of mostly Mesozoic-aged sedimentation in an area of North America in and around Capitol Reef National Park, on the Colorado Plateau in southeastern Utah.
The Powderhorn Wilderness is a 62,050-acre (251.1 km2) wilderness area in Hinsdale and Gunnison Counties, Colorado, USA, located 5 miles (8.0 km) northeast of Lake City. Most of the northern part of the area, 48,115 acres (194.71 km2), about 77.5%, is located on Bureau of Land Management land and its southern portion, 13,935 acres (56.39 km2), about 22.5%, is located within the Gunnison National Forest. Elevations in the wilderness range from 8,500 feet (2,600 m) at the West Fork Powderhorn Creek to 12,661 feet (3,859 m) at the summit of Calf Creek Plateau.
The Coconino National Forest is a 1.856-million acre United States National Forest located in northern Arizona in the vicinity of Flagstaff. Originally established in 1898 as the "San Francisco Mountains National Forest Reserve", the area was designated a U.S. National Forest in 1908 when the San Francisco Mountains National Forest Reserve was merged with lands from other surrounding forest reserves to create the Coconino National Forest. Today, the Coconino National Forest contains diverse landscapes, including deserts, ponderosa pine forests, flatlands, mesas, alpine tundra, and ancient volcanic peaks. The forest surrounds the towns of Sedona and Flagstaff and borders four other national forests; the Kaibab National Forest to the west and northwest, the Prescott National Forest to the southwest, the Tonto National Forest to the south, and the Apache-Sitgreaves National Forest to the southeast. The forest contains all or parts of ten designated wilderness areas, including the Kachina Peaks Wilderness, which includes the summit of the San Francisco Peaks. The headquarters are in Flagstaff. There are local ranger district offices in Flagstaff, Happy Jack, and Sedona.
The Uncompahgre Plateau in western Colorado is a distinctive large uplift part of the Colorado Plateau. Uncompahgre is a Ute word that describes the water: "Dirty Water" or "Rocks that make Water Red".
The West Elk Mountains are a high mountain range in the west-central part of the U.S. state of Colorado. They lie primarily within the Gunnison National Forest, and part of the range is protected as the West Elk Wilderness. The range is primarily located in Gunnison County, with small parts in eastern Delta and Montrose counties.
The Oregon Coast Range, often called simply the Coast Range and sometimes the Pacific Coast Range, is a mountain range, in the Pacific Coast Ranges physiographic region, in the U.S. state of Oregon along the Pacific Ocean. This north-south running range extends over 200 miles (320 km) from the Columbia River in the north on the border of Oregon and Washington, south to the middle fork of the Coquille River. It is 30 to 60 miles wide and averages around 1,500 feet (460 m) in elevation above sea level. The coast range has three main sections, a Northern, Central, and Southern.
Arizona is a landlocked state situated in the southwestern region of the United States of America. It has a vast and diverse geography famous for its deep canyons, high- and low-elevation deserts, numerous natural rock formations, and volcanic mountain ranges. Arizona shares land borders with Utah to the north, the Mexican state of Sonora to the south, New Mexico to the east, and Nevada to the northwest, as well as water borders with California and the Mexican state of Baja California to the southwest along the Colorado River. Arizona is also one of the Four Corners states and is diagonally adjacent to Colorado.
The Coast Range ecoregion is a Level III ecoregion designated by the Environmental Protection Agency (EPA) in the U.S. states of Washington, Oregon, and California. It stretches along the Pacific Coast from the tip of the Olympic Peninsula in the north to the San Francisco Bay in the south, including Grays Harbor, Willapa Bay, and the Long Beach Peninsula in Washington, the entire length of the Oregon Coast, and the Northern California Coast. Named for the Coast Range mountains, it encompasses the lower elevations of the Olympic Mountains, the Oregon Coast Range, the Californian North Coast Ranges, and surrounding lowlands.
The Cascades ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency (EPA) in the U.S. states of Washington, Oregon, and California. Somewhat smaller than the Cascade mountain range for which it is named, the ecoregion extends north to Snoqualmie Pass, near Seattle, and south to Hayden Pass, near the Oregon-California border, including the peaks and western slopes of most of the High Cascades. A discontiguous section is located on Mount Shasta in California.
The Eastern Cascades Slopes and Foothills ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency (EPA) in the U.S. states of Oregon, Washington, and California. In the rain shadow of the Cascade Range, the eastern side of the mountains experiences greater temperature extremes and receives less precipitation than the west side. Open forests of ponderosa pine and some lodgepole pine distinguish this region from the Cascades ecoregion, where hemlock and fir forests are more common, and from the lower, drier ecoregions to the east, where shrubs and grasslands are predominant. The vegetation is adapted to the prevailing dry, continental climate and frequent wildfire. Volcanic cones and buttes are common in much of the region.
The Blue Mountains ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency (EPA) in the Pacific Northwest, mainly in the state of Oregon, with small areas over the state border in Idaho and southeastern Washington. It is also contiguous with the World Wildlife Fund's Blue Mountain forests ecoregion.
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. At 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.
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