Wikipedia:Today's featured article/May 15, 2006
From Wikipedia, the free encyclopedia
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. Nearly 10,000 feet (3000 m) of sedimentary strata are found in the Capitol Reef area, representing nearly 200 million years of geologic history of the south-central part of the U.S. state of Utah. Rock layers in the area reveal ancient climates as varied as rivers and swamps (Chinle Formation), Sahara-like deserts (Navajo Sandstone), and shallow ocean. The sea retreated, leaving streams, lakes and swampy plains to become the resting place for sediments. From 70 to 50 million years ago, the Laramide orogeny, a major mountain building event in western North America, created the Rocky Mountains to the east. The uplift possibly acted on a buried fault to form the area's Waterpocket Fold. More recent uplift of the entire Colorado Plateau and the resulting erosion has exposed this fold at the surface only within the last 15 to 20 million years. Ice ages in the Pleistocene increased the rate of precipitation and erosion. The cracked upper parts of the Waterpocket Fold were especially affected and the fold itself was exposed and dissected. (More...)
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