Explain the process that forms a fault-block mountain.
2007-01-15 16:42:17 · 2 answers · asked by TearDropp 1 in Science & Mathematics ➔ Earth Sciences & Geology
Flat land becomes mountains and valleys when portions of the land are uplifted. Varying forces within the earth's crust can cause this uplift. Forces pushing toward each other can make the rock fold or fault (break and move). The Rocky Mountains are predominantly folded mountains, but in some areas there are faults.
Pushing can also cause rock within the crust to break and move forming fault block mountains such as those in Utah's Great Basin: the Wasatch, Oquirrh, and Stansbury Mountains.
Volcanic action can also form mountains. Molten rock (magma) that erupts at the earth's surface as flowing lava, cinders, or ash forms volcanic mountains. Such mountains in Utah include the Tushan Mountains and Black Rock Volcano.
Melted rock that pushes up the layered rock but does not erupt cools into igneous rock beneath the surface forming dome-shaped mountains. In Utah, dome-shaped mountains include the LaSal, Henry, and Abajo Mountains, and Navajo Mountain.
All mountains undergo the natural wearing down process of erosion. If mountain building forces are not active, mountains will again become flat land.
Fault-block mountains are produced when normal (near vertical) faults fracture a section of continental crust. Vertical motion of the resulting blocks, sometimes accompanied by tilting, can then lead to high escarpments. These mountains are basically formed by the earth's crust being stretched and extended. Tilted blocks are common in the Basin and Range region of the western United States. Level blocks lead to the horst and graben terrain seen in northern Europe. Fault block mountains commonly accompany rifting and are indicators of tensional tectonic forces.
Fault block mountains are formed as a result of a combination of tension and uplift forces. The stretching and cracking of the crust gives the mountains their appearance and name.
2007-01-15 16:49:33 · answer #1 · answered by journeythroughlife85 2 · 0⤊ 0⤋
The mantle circulates due to heating from radioactive decay of uranium, thorium and potassium. When this circulation occurs under continents it causing extension of the continental plate. This extension thins the continents and causes downthrown basins and upthrown ridges. Fault-block nountains are the name of these upthrown ridges.
2007-01-16 07:13:42 · answer #2 · answered by Amphibolite 7 · 0⤊ 0⤋