How Are Mountains Formed?Mountains are formed over long periods of time by forces of the earth. Mountains just don’t appear in any place. Most are formed when plates, or huge pieces of the Earth’s crust, pull and push against each other.
Greatmountain ranges are formed by the movement of tectonic plates. Convectioncurrents deep in the mantle of the earth, begins to well up towards thesurface. As the pressure increases, it sets the crustal plates in motion. There are different kinds of mountains – Volcanic, Folded, Fault-block, andDome mountains. Volcanic mountains are formed when magma comes upthrough cracks in the Earth’s crust and explodes out lava and ash. TheHawaiian volcanoes, Mt.
Hood, Mt. Etna, Vesuvius, and Mt. Saint Helens areexamples of volcanic mountains. Rocks are hard but in time they can bend orfold producing Folded mountains.
The Alps formed as the Eurasian platepushed against the African plate. Other examples of folded mountains are theRockies, Himalayas, Appalayas, and the Andes. Fault-block mountains areformed when one plate pushes or pulls away from another plate. In the Earth,hot currents of magma or molten rock may well up and crack the weakenedcrust above. As the crust cracks, blocks of rock rise or fall formingFault-block mountains. Examples of these mountains are the Sierra Nevada inCalifornia and the Grand Tetons in Wyoming.
Dome mountains are formedby the same kind of molten rock that forms Volcanic mountains. As magmacomes up in a crack in the Earth’s crust, it does not come to the surface, butthe molten rock pushes the ground up into a dome. Examples are Yosemite’sHalf Dome, the Adirondacks in New York, and the Black Hills in SouthDakota. Some mountains started at the bottom of the sea. Scientists found thatout when they took limestone off Mt.
Everest and found dead sea creatures. Limestone is a kind of rock that is formed very slowly over thousands of years. Animals and plants that get stuck in limestone are called fossils. Limestone and fossils are common in most mountains that originated at thebottom of the sea.
It is really amazing how mountains are formed by forcesof the earth.