Colorado Plateau - Geography

Geography

The province is bounded by the Rocky Mountains in Colorado, and by the Uinta Mountains and Wasatch Mountains branches of the Rockies in northern and central Utah. It is also bounded by the Rio Grande Rift, Mogollon Rim and the Basin and Range. Isolated ranges of the Southern Rocky Mountains such as the San Juan Mountains in Colorado and the La Sal Mountains in Utah intermix into the central and southern parts of the Colorado Plateau. It is composed of seven sections:

• Uinta Basin Section
• High Plateaus Section
• Grand Canyon Section
• Canyon Lands Section
• Navajo Section
• Datil-Mogollon Section
• Acoma-Zuni Section

As the name implies, the High Plateaus Section is, on average, the highest section. North-south trending normal faults that include the Hurricane, Sevier, Grand Wash, and Paunsaugunt separate the section's component plateaus. This fault pattern is caused by the tensional forces pulling apart the adjacent Basin and Range province to the west, making this section transitional.

Occupying the southeast corner of the Colorado Plateau is the Datil Section. Thick sequences of mid-Tertiary to late-Cenozoic-aged lava covers this section.

Development of the province has in large part been influenced by structural features in its oldest rocks. Part of the Wasatch Line and its various faults form the western edge of the province. Faults that run parallel to the Wasatch Fault that lies along the Wasatch Range form the boundaries between the plateaus in the High Plateaus Section. The Uinta Basin, Uncompahgre Uplift, and the Paradox Basin were also created by movement along structural weaknesses in the region's oldest rock.

In Utah, the province includes several higher fault-separated plateaus:

• Awapa Plateau
• Aquarius Plateau
• Kaiparowits Plateau
• Markagunt Plateau
• Paunsaugunt Plateau
• Sevier Plateau
• Fishlake Plateau
• Pavant Plateau
• Gunnison Plateau and the
• Tavaputs Plateau.

Some sources also include the Tushar Mountain Plateau as part of the Colorado Plateau, but others do not. The mostly flat-lying sedimentary rock units that make up these plateaus are found in component plateaus that are between 1500 m (5000 ft) to over 3350 m (11,000 ft) above sea level. A supersequence of these rocks is exposed in the various cliffs and canyons (including the Grand Canyon) that make up the Grand Staircase. Increasingly younger east-west trending escarpments of the Grand Staircase extend north of the Grand Canyon and are named for their color:

• Chocolate Cliffs,
• Vermillion Cliffs,
• White Cliffs,
• Gray Cliffs, and the
• Pink Cliffs.

Within these rocks are abundant mineral resources that include uranium, coal, petroleum, and natural gas. Study of the area's unusually clear geologic history (which is laid bare due to the arid and semiarid conditions) has greatly advanced that science.

A rain shadow from the Sierra Nevada far to the west and the many ranges of the Basin and Range means that the Colorado Plateau receives 15 to 40 cm (6 to 16 in.) of annual precipitation. Higher areas receive more precipitation and are covered in forests of pine, fir, and spruce.

Though it can be said that the Plateau roughly centers on the Four Corners, Black Mesa in northern Arizona is much closer to the east-west, north-south midpoint of the Plateau Province. Lying southeast of Glen Canyon and southwest of Monument Valley at the north end of the Hopi Reservation, this remote coal-laden highland has about half of the Colorado Plateau's acreage north of it, half south of it, half west of it, and half east of it.