This Satellite view of Utah shows a variety of geologic features.  Most notable are the snow-capped and east-west trending Uinta Mountains, the north-south trending Basin and Range Province and the Great Salt Lake.  The rocks shown range in age from Precambrian (over 1 billion years old) to Recent.

Lehi Hintze of Brigham Young University has divided the last 1 billion years of Utah's geologic history into the six stages shown below (Hintze 1988).  Although our modern landscape (valleys, benches, surrounding mountains) is the result of relatively recent processes, the rocks comprising the landscape possess a highly varied history.

Six Stages in the Geologic History of Utah

(refer to the Geologic Time Scale for approximate ages of the time intervals noted below)

I Quiet Shallow-Water Marine Conditions
  Late Precambrian through Devonian (1,200 - 350 my)

Utah was located near the equator and covered by shallow seas.  Initially sandstones were deposited, followed by shales, then limestones and dolostones.  Superimposed on this pattern of quiet sedimentation were several advances and withdrawls of the sea, resulting in the stacking of various rock pages (e.g. sandstone, shale, limestone, shale).   Rocks deposited in this interval are visible in Ogden, Box Elder and Logan Canyons (Image,  Image).  Many of these rocks are quite fossiliferous.

II Formation of Domes and Basins
   Mississippian through Early Triassic (350 - 200 my)

During this interval broad uplifts (domes) and depressions (basins) were formed, including the Oquirrh Basin in northcentral Utah and the Paradox Basin to the south.  Basins are usually characterized by very thick sedimentary sequences since there is space for sediments to accumulate.  The very thick (20,000') thick Oquirrh Formation visible in Provo Canyon is a good example of this.  The majority of the rock types were still shallow marine.

III The Sevier Orogeny
   Jurassic through Cretaceous (200 - 80 my)

This was a major orogenic (mountain building) event caused by North America moving westward and colliding with the Pacific Ocean plate.  Large sheets of rock (thrust sheets) were moved from west to east (up to 50 km or more).   For example Cache Valley is located on the Willard thrust sheet, which is a separate thrust from that underlying the Ogden Valley.  Considerable folding also occurred, such as the Logan Syncline in Logan Canyon and the "Z" fold in Ogden Canyon (Image) .

Rocks deposited during this interval include both marine and nonmarine rocks.  The Jurassic age Navajo, Entrada, and Morrison Formations are good examples of the latter.  The Navajo was deposited as windblown desert sand dunes (Image).  These are well exposed in Zion Canyon National Part.  The Morrison is famous for its dinosaur fauna and can be viewed at Dinosaur National Monument (Image).  During the Cretaceous Period much of the coal mined in eastern Utah was deposited in deltaic and lagoonal conditions.

IV The Laramide Orogeny
    Cretaceous through Paleocene (80 - 40 my)

The Laramide was a continuation of the earlier Sevier Orogeny.  The deformation shifted further east, resulting in the uplift of the Uinta Mountains (Image) and Colorado Rockies.  Sediments were deposited in the basins between the uplifts. These post-Laramide basin fills include the Wasatch and equivalent formations, which are usually a bright red conglomerate (Image)  (visible above Tony Grove Lake in Logan Canyon and on I-80 east of Ogden), and the Green River Formation, which was deposited in a very extensive freshwater lake.  The Green River Formation is famous for fossil fish, insects and plants, many of which are on display at Fossil Butte National Monument in Kemmerer, Wyoming (Image,  Image).

V Acidic Volcanism
   Oligocene (40 - 25 my)

Eventually the westward movement of the North American Plate resulted in the overriding of the Pacific spreading center.  This resulted in partial melting of the crust and extensive volcanism occurred.  Extensive welded tuffs  covered much of the area of Utah.  Remnants are visible at Crystal Peak (Image) and Topaz Mountain.  There were also granitic intrusions, for example the Little Cottonwood (Image) and Bingham Stocks (Image), which are the basis for Utah's mining industry.

VI Extension and Basic Volcanism
    Miocene through Recent (25 - 0 my)

Over the last 15 million years the western United States has experienced both uplift and tensional (pull-apart) forces.  This is due to the presence of a spreading center beneath us.  This has resulted in the uplift of the Colorado Plateau and associated canyon cutting - for example, Zion (Image) and Bryce Canyons (Image), Canyon Lands (Image).  Another consequence of the tensional forces is the development of the Basin and Range Province, which consists of a series of fault-bounded mountains and valleys extending from Utah to California.  The Wasatch Fault (Image) is due to these tensional forces.

The style of volcanism shifted from welded tuffs and granitic intrusions to the formation of cinder cones (Image) and basaltic flows (Image).

Finally, during the last several hundred thousand years, Utah experienced the Pleistocene ice age.  This resulted in alpine glaciation (its effects are beautifully exposed in Little Cottonwood Canyon - Image) and extensive lakes (collectively referred to as Lake Bonneville).  The lake was quite deep (up to 1,000' deep in the Salt Lake valley), filling our valleys up to the 5,100' level and resulting in the familiar shoreline "benches" that are so desirable for home building (Image).

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