Canyon Lands
Encyclopedia
The Canyon Lands Section of the Colorado Plateaus is a physiographic section
of the larger Colorado Plateau
s province, which in turn is part of the larger Intermontane Plateaus
physiographic division. They are a desolate but spectacularly scenic sandstone area of southeastern Utah. Dominated by canyons (as the name implies) this section has four large upwarps between which are structural basins. Very little faulting is associated with the upwarps or basins. Other distinctive features of the Canyon Lands Section are the laccolith
ic mountains, like the Henry Mountains
and the La Sal Mountains. These are structural domes
.
Into it from the east, through a deep meandering gorge, flows the turbid San Juan River which, with its tributaries, drains a far-reaching area, including the La Plata Mountains, the San Juan Mountains and other lesser ranges on the Continental Divide, the Chuska Mountains, and enormous areas of mesa land in the interior of the basin. From the Wasatch and Aquarius Plateaus on the west come other, but lesser, silt-laden streams, all carving the deep, winding canyons which have given this country its name and developed a weirdly dissected landscape. The Colorado River
is the largest such stream.
In northeastern Arizona is Monument Valley
, where sharp spires, obelisks, and tower-like masses of rock rise hundreds of feet above their surroundings. At the eastern margin of the Canyon Lands is the Mesa Verde, a huge cuesta
that has been deeply dissected by streams. Here in great recesses in the canyon walls are found the ruins of ancient cliff dwellings.
East of the Little Colorado River
are the brilliantly colored areas known as the Painted Desert
. Here the rocks show gorgeous colors in strata that are gently inclined and present a series of cliffs that are slowly migrating as weathering and erosion proceed.
The area north of the canyon of the San Juan River has several surfaces varying from 6,000 to 7000 ft (2,133.6 m) above sea level. There are bold escarpments bordering some of these plateaus, canyons with steep walls, and a group of mesas called the Tables of the Sun, and several national monuments containing natural bridges.
The Canyon Lands terminate, approximately, at a third, intermittent barrier formed by the Paria Plateau, Black Mesa, and the Chuska Mountain mass.
occupying the majority of Emery County, Utah. This feature is a large northeast trending upwarp approximately 75 miles (120.7 km) long and 30 miles (48.3 km) wide that is part of a much larger, double-plunging anticline (e.g., dome) structure. This large, regional fold exposes rocks of Pennsylvanian
through Cretaceous
age. Resistant beds of sandstone are exposed as hogbacks on the steeply upturned east and west flanks of the anticline and are referred to locally as “reefs.” Three perennial rivers (the Muddy, San Rafael, and Price) flow eastward across the San Rafael Swell into the Green and Colorado River system.
Physiographic regions of the world
The physiographic regions of the world are a means of defining the Earth's landforms into distinct regions based upon classic 1916 three-tiered approach defining divisions, provinces, and sections...
of the larger Colorado Plateau
Colorado Plateau
The Colorado Plateau, also called the Colorado Plateau Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. The province covers an area of 337,000 km2 within western Colorado, northwestern New Mexico,...
s province, which in turn is part of the larger Intermontane Plateaus
Intermontane Plateaus
Physiographic regions of the U.S. InteriorSee:legendIn some places,high plateaus lie between the mountain ranges, for example,the plateau of Anatolia in Turkey and the plateau of Tibet.These are called "Intermontane plateaus"....
physiographic division. They are a desolate but spectacularly scenic sandstone area of southeastern Utah. Dominated by canyons (as the name implies) this section has four large upwarps between which are structural basins. Very little faulting is associated with the upwarps or basins. Other distinctive features of the Canyon Lands Section are the laccolith
Laccolith
A laccolith is a sheet intrusion that has been injected between two layers of sedimentary rock. The pressure of the magma is high enough that the overlying strata are forced upward, giving the laccolith a dome or mushroom-like form with a generally planar base.Laccoliths tend to form at relatively...
ic mountains, like the Henry Mountains
Henry Mountains
The Henry Mountains are located in the southeastern portion of the U.S. state of Utah and run in a generally north-south direction, extending over a distance of about 30 miles . They were named by John Wesley Powell in honour of Joseph Henry, the first secretary of the Smithsonian Institution. The...
and the La Sal Mountains. These are structural domes
Dome (geology)
In structural geology, a dome is a deformational feature consisting of symmetrically-dipping anticlines; their general outline on a geologic map is circular or oval...
.
Into it from the east, through a deep meandering gorge, flows the turbid San Juan River which, with its tributaries, drains a far-reaching area, including the La Plata Mountains, the San Juan Mountains and other lesser ranges on the Continental Divide, the Chuska Mountains, and enormous areas of mesa land in the interior of the basin. From the Wasatch and Aquarius Plateaus on the west come other, but lesser, silt-laden streams, all carving the deep, winding canyons which have given this country its name and developed a weirdly dissected landscape. The Colorado River
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...
is the largest such stream.
In northeastern Arizona is Monument Valley
Monument Valley
Monument Valley is a region of the Colorado Plateau characterized by a cluster of vast sandstone buttes, the largest reaching above the valley floor. It is located on the northern border of Arizona with southern Utah , near the Four Corners area...
, where sharp spires, obelisks, and tower-like masses of rock rise hundreds of feet above their surroundings. At the eastern margin of the Canyon Lands is the Mesa Verde, a huge cuesta
Cuesta
In structural geology and geomorphology, a cuesta is a ridge formed by gently tilted sedimentary rock strata in a homoclinal structure. Cuestas have a steep slope, where the rock layers are exposed on their edges, called an escarpment or, if more steep, a cliff...
that has been deeply dissected by streams. Here in great recesses in the canyon walls are found the ruins of ancient cliff dwellings.
East of the Little Colorado River
Little Colorado River
The Little Colorado River is a river in the U.S. state of Arizona, providing the principal drainage from the Painted Desert region. Together with its major tributary, the Puerco River, it drains an area of about in eastern Arizona and western New Mexico...
are the brilliantly colored areas known as the Painted Desert
Painted Desert
Painted Desert may refer to:In places:* Painted Desert, Arizona, an area of badlands in the southwestern United States* Painted Desert , a mountainous area in south-central Australia...
. Here the rocks show gorgeous colors in strata that are gently inclined and present a series of cliffs that are slowly migrating as weathering and erosion proceed.
The area north of the canyon of the San Juan River has several surfaces varying from 6,000 to 7000 ft (2,133.6 m) above sea level. There are bold escarpments bordering some of these plateaus, canyons with steep walls, and a group of mesas called the Tables of the Sun, and several national monuments containing natural bridges.
The Canyon Lands terminate, approximately, at a third, intermittent barrier formed by the Paria Plateau, Black Mesa, and the Chuska Mountain mass.
Geology
Perhaps the dominant physical feature within the area is the San Rafael SwellSan Rafael Swell
The San Rafael Swell is a large geologic feature located in south-central Utah, USA about 30 miles west of Green River, Utah. The San Rafael Swell, approximately by , consists of a giant dome-shaped anticline of sandstone, shale, and limestone that was pushed up during the Paleocene Laramide...
occupying the majority of Emery County, Utah. This feature is a large northeast trending upwarp approximately 75 miles (120.7 km) long and 30 miles (48.3 km) wide that is part of a much larger, double-plunging anticline (e.g., dome) structure. This large, regional fold exposes rocks of Pennsylvanian
Pennsylvanian
The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly . As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain...
through Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
age. Resistant beds of sandstone are exposed as hogbacks on the steeply upturned east and west flanks of the anticline and are referred to locally as “reefs.” Three perennial rivers (the Muddy, San Rafael, and Price) flow eastward across the San Rafael Swell into the Green and Colorado River system.