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Basin and Range ProvinceGeology of National Parks

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Locality Map

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Alluvial Fans

• Semicircular deposits at the base of mountain streams, where the gradient decreases as they flow onto the valley floor

• They violate the Law of Original Horizontality, because deposits at the edge of the fan aren’t horizontal

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Alluvial Fans, Sangre De Cristo Mountains, Colorado

• East of Saguache, south central Colorado• Three alluvial fans are visible

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Evaporite Deposits in Basins

• Interior drainage possible Streams run into a basin, which may

accumulate some water Evaporation rates are so high, the lake never

gets deep enough to spill over the lowest point in its rim

Rather, the water simply becomes more saline, or dries up entirely

Salt deposits (evaporites) form

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Playa Lake With Salt Deposits

• A playa is an ephemeral lake, created by interior drainage and evaporation • Near Shiprock, New Mexico

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Basin and Range

• Digital Elevation Model (DEM) created from elevation data

• Clearly shows the “roller coaster”

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The Lonliest Road

• US 50 in Nevada, as designated by Life magazine

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Glacial Lake Bonneville

• Glacial Lake Bonneville was one of several large Pleistocene lakes

• Great Salt Lake and the Bonneville Salt Flats are remnants

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Bonneville Salt Flats

• The area west of Salt Lake Utah to near the Nevada border is a large, flat expanse of evaporite salt

• It supports almost no vegetation• The salt flats are a remnant of Pleistocene glacial Lake Bonneville, which covered a much

larger area• As the glacial lake evaporated, salts began to accumulate, and are still accumulating today