For example, the floor of a basin in Wyoming, Jackson Hole, is 6,000 feet (1,830 meters) above sea level, while the adjacent Teton Range rises to over 13,000 feet (4,000 meters). There the whole landscape is moving upward, with the ranges rising a little faster than the adjacent basins. First, much of the region-particularly the northern portion-is well above sea level.
#Shield volcanoes diagrams full
Lillie, Wells Creek Publishers, 92 pp., 2015, The topography of the Basin and Range Province and Rio Grande Rift reveals the full range of characteristics of a continental rift zone.
Modified from “Beauty from the Beast: Plate Tectonics and the Landscapes of the Pacific Northwest,” by Robert J. Earthquakes (white stars) occur when the fault lines separating the basins and ranges suddenly let go. National Park Service sites in continental rift zones reveal long mountain ranges separated by deep valleys (basins) that are partially filled with sedimentary and volcanic material. Earthquakes, fault-block mountains, and volcanism at Guadalupe Mountains National Park and Bandelier and White Sands national monuments are consequences of the ongoing continental rifting.īasin & Range Province and Rio Grande Rift The Rio Grande Rift is an arm of the Basin and Range Province extending across westernmost Texas, New Mexico, and southern Colorado. Prominent planar surfaces (fault escarpments) along range fronts are evidence that the region continues to rip apart-erosion would smooth them out if the fault movement stopped. It is similar to the East African Rift, where volcanic materials and sedimentary layers deposited by rivers and lakes partially fill rift valleys. The Basin and Range Province is thus a high-elevation region that includes all of Nevada and portions of Wyoming, Utah, California, and Arizona, and extends into southern Oregon, Idaho, and Montana. If the plate is capped by thick continental crust, the resulting continental rift zone rises high above sea level. The underlying asthenosphere rises and expands like a hot-air balloon, elevating a broad region. Where tectonic plates move away from one another the lithosphere thins. The dark-colored lava flows formed over a billion years ago in the Keweenawan Rift, as the ancient North American continent tried to rip apart and low-silica (basaltic) magma poured out on the surface.Īctive Continental Rifting in the Western United States TICA-Timpanogos Cave National Monument, Utah.SUCR-Sunset Crater National Monument, Arizona.ORPI-Organ Pipe Cactus National Monument, Arizona.MOJA-Mojave National Preserve, California.LABE-Lava Beds National Monument, California.LAKE-Lake Mead National Recreation Area, Arizona & Nevada.JOTR-Joshua Tree National Park, California.GRBA-Great Basin National Park, Nevada- \.GRTE-Grand Teton National Park, Wyoming.GRCA-Grand Canyon National Park, Arizona.
0 kommentar(er)
