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Colorado Laramide Highlands at 57 million years
Colorado Laramide Highlands at 57 million years
::2012/11/29::
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2
102 - M Laramide Orogeny
102 - M Laramide Orogeny
::2014/08/12::
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3
Compression during the Laramide orogeny
Compression during the Laramide orogeny
::2014/08/05::
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Grand Canyon Formation
Grand Canyon Formation
::2010/06/25::
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Versus The Collective -- Laramide Orogeny
Versus The Collective -- Laramide Orogeny
::2011/06/15::
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THE GRAND CANYON: 10 interesting facts!
THE GRAND CANYON: 10 interesting facts!
::2014/06/06::
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Labwork (unlisted)
Labwork (unlisted)
::2013/01/06::
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Flatirons of Boulder Colorado
Flatirons of Boulder Colorado
::2012/09/19::
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Souris Rock Shop in Souris, Manitoba
Souris Rock Shop in Souris, Manitoba
::2012/12/12::
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Grand Staircase Vermillion Cliffs
::2013/10/28::
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::2013/09/15::
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Hiking Mosquito Range.
Hiking Mosquito Range.
::2010/09/22::
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The Grand Canyon
The Grand Canyon
::2009/05/21::
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Josh
Josh's Rocky Outcrop
::2014/08/12::
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15
DriveAbout 56 -  Grand Canyon
DriveAbout 56 - Grand Canyon
::2008/08/20::
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Grand Canyon
Grand Canyon
::2008/01/16::
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Scenic Drive on Rocky Mountain, CO (GoPro HERO3)
Scenic Drive on Rocky Mountain, CO (GoPro HERO3)
::2014/01/11::
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102 - M Nevadan Orogeny
102 - M Nevadan Orogeny
::2014/08/12::
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Southwest Utah: Nature
Southwest Utah: Nature's Cameo: Bryce Canyon National Park circa 1930s Ford
::2012/11/26::
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102 - M Sevier Orogeny
102 - M Sevier Orogeny
::2014/08/12::
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Franklin Mountain State Park
Franklin Mountain State Park
::2012/11/23::
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22
DriveAbout 47 - Canyonlands National Park, Utah (English)
DriveAbout 47 - Canyonlands National Park, Utah (English)
::2008/08/16::
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DriveAbout 49 - Canyonlands National Park, Utah
DriveAbout 49 - Canyonlands National Park, Utah
::2008/08/17::
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DriveAbout 51 - Canyonlands National Park, Utah
DriveAbout 51 - Canyonlands National Park, Utah
::2008/08/19::
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DriveAbout 48 - Canyonlands National Park, Utah
DriveAbout 48 - Canyonlands National Park, Utah
::2008/08/17::
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DriveAbout 52  FUNNY - Romano tipico on the road
DriveAbout 52 FUNNY - Romano tipico on the road
::2008/08/18::
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DriveAbout 50 - SOUND - Canyonlands National Park, Utah
DriveAbout 50 - SOUND - Canyonlands National Park, Utah
::2008/08/17::
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::2008/07/16::
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Orogeny
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::2012/01/08::
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Beryllium Unearthed (Part 1-B)
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::2010/05/07::
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102 - NOVA scienceNOW   24   Mass Extinction
102 - NOVA scienceNOW 24 Mass Extinction
::2014/08/12::
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The Carolina Bays as evidence of a cosmic impact.
The Carolina Bays as evidence of a cosmic impact.
::2014/07/13::
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102 - M dinosaur types
102 - M dinosaur types
::2014/08/12::
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102 - LP amniotic egg
102 - LP amniotic egg
::2014/08/12::
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Subduction
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::2014/07/29::
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36
NMPBS ¡Colores!: Antoine Predock
NMPBS ¡Colores!: Antoine Predock
::2013/05/10::
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37
Demise of the Farallon Plate Beneath North America (2001)
Demise of the Farallon Plate Beneath North America (2001)
::2008/10/08::
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38
Versus The Collective -- Vox Populi
Versus The Collective -- Vox Populi
::2011/06/15::
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39
Cretaceous
Cretaceous
::2014/08/17::
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40
102 - LP cyclothem
102 - LP cyclothem
::2014/08/12::
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41
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Gulf of Mexico
::2014/09/02::
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All About - Geology of the Grand Canyon area
All About - Geology of the Grand Canyon area
::2014/07/04::
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Buckhorn Draw Pictograph Panel /  Rock Art / Petroglyph / San Rafael Swell In South-Central Utah
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::2014/09/10::
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Versus The Collective -- "Commandeer That Satellite!"
Versus The Collective -- "Commandeer That Satellite!"
::2011/06/14::
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45
102 - M Jurassic Rifting
102 - M Jurassic Rifting
::2014/08/12::
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46
Grand Canyon
Grand Canyon
::2014/04/29::
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47
The granite narrows
The granite narrows
::2014/08/05::
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48
Chapter 11 Lecture Notes - Mountain Building / Geologic Structures - Part 3 - pvONLINE
Chapter 11 Lecture Notes - Mountain Building / Geologic Structures - Part 3 - pvONLINE
::2013/04/23::
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All About - Geology of the Capitol Reef area
All About - Geology of the Capitol Reef area
::2014/07/04::
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Young Appalachian Mountains.wmv
Young Appalachian Mountains.wmv
::2012/04/15::
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From Wikipedia, the free encyclopedia
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The Laramide orogeny was a period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. The exact duration and ages of beginning and end of the orogeny are in dispute. The Laramide orogeny occurred in a series of pulses, with quiescent phases intervening. The major feature that was created by this orogeny was deep-seated, thick-skinned deformation, with evidence of this orogeny found from Canada to northern Mexico, with the easternmost extent of the mountain-building represented by the Black Hills of South Dakota. The phenomenon is named for the Laramie Mountains of eastern Wyoming. The Laramide orogeny is sometimes confused with the Sevier orogeny, which partially overlapped it in time and space.[1]

The Laramide orogeny was caused by subduction of a plate at a shallow angle.

The orogeny is commonly attributed to events off the west coast of North America, where the Kula and Farallon Plates were sliding under the North American plate. Most hypotheses propose that the angle of subduction became shallow, and as a consequence, no magmatism occurred in the central west of the continent, and the underlying oceanic lithosphere actually caused drag on the root of the overlying continental lithosphere. One cause for shallow subduction may have been an increased rate of plate convergence. Another proposed cause was subduction of thickened oceanic crust.

Magmatism associated with subduction occurred not near the plate edges (as in the volcanic arc of the Andes, for example), but far to the east, called the Coast Range Arc. Geologists call such a lack of volcanic activity near a subduction zone a magmatic null. This particular null may have occurred because the subducted slab was in contact with relatively cool continental lithosphere, not hotter asthenosphere.[2] One result of shallow angle of subduction and the drag that it caused was a broad belt of mountains, some of which were the progenitors of the Rocky Mountains. Part of the proto-Rocky Mountains would be later modified by extension to become the Basin and Range Province.

Ecological consequences[edit]

According to paleontologist Thomas M. Lehman, the Laramide orogeny triggered "the most dramatic event that affected Late Cretaceous dinosaur communities in North America prior to their extinction."[3] This turnover event saw the replacement of specialized and highly ornamented centrosaurine and lambeosaurines by more primitive upland dinosaurs in the south, while northern biomes became dominated by Triceratops with a greatly reduced hadrosaur community.[4]

Basins and mountains[edit]

The Laramide orogeny produced intermontane structural basins and adjacent mountain blocks by means of deformation. This style of deformation is typical of continental plates adjacent to convergent margins of long duration that have not sustained continent/continent collisions. This tectonic setting produces a pattern of compressive uplifts and basins, with most of the deformation confined to block edges. Twelve kilometers of structural relief between basins and adjacent uplifts is not uncommon. The basins contain several thousand meters of Paleozoic and Mesozoic sedimentary rocks that predate the Laramide orogeny. As much as 5000 m of Cretaceous and Cenozoic sediments filled these orogenically defined basins. Deformed Paleocene and Eocene deposits record continuing orogenic activity.[5]

During the Laramide orogeny, basin floors and mountain summits were much closer to sea level than today. After the seas retreated from the Rocky Mountain region, floodplains, swamps, and vast lakes developed in the basins. Drainage systems imposed at that time persist today. Since the Oligocene, episodic epeirogenic uplift gradually raised the entire region, including the Great Plains, to present elevations. Most of the modern topography is the result of Pliocene/Pleistocene events, including additional uplift, glaciation of the high country, and denudation and dissection of older Cenozoic surfaces in the basin by fluvial processes.[5]

Topographic map of the Bighorn Basin (highlighted in orange), formed by the Laramide Orogeny

In the United States, these distinctive intermontane basins occur principally in the central Rocky Mountains from Colorado and Utah (Uinta Basin) to Montana and are best developed in Wyoming, with the Big Horn, Powder River, and Wind River being the largest. Topographically, the basin floors resemble the surface of the western Great Plains, except for vistas of surrounding mountains.[5]

At most boundaries, Paleozoic through Paleogene units dip steeply into the basins off uplifted blocks cored by Precambrian rocks. The eroded steeply dipping units form hogbacks and flatirons. Many of the boundaries are thrust or reverse faults. Although other boundaries appear to be monoclinal flexures, faulting is suspected at depth. Most bounding faults show evidence of at least two episodes of Laramide (Late Cretaceous and Eocene) movement, suggesting both thrust and strike-slip types of displacement.[5]

See also[edit]

Footnotes[edit]

References[edit]

External links[edit]

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