How up in a crack in the
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. Great
mountain ranges are formed by the movement of tectonic plates. Convection
currents deep in the mantle of the earth, begins to well up towards the
surface. As the pressure increases, it sets the crustal plates in motion.
There are different kinds of mountains – Volcanic, Folded, Fault-block, and
Dome mountains. Volcanic mountains are formed when magma comes up
through cracks in the Earth’s crust and explodes out lava and ash. The
Hawaiian volcanoes, Mt. Hood, Mt. Etna, Vesuvius, and Mt. Saint Helens are
examples of volcanic mountains. Rocks are hard but in time they can bend or
fold producing Folded mountains. The Alps formed as the Eurasian plate
pushed against the African plate. Other examples of folded mountains are the
Rockies, Himalayas, Appalayas, and the Andes. Fault-block mountains are
formed 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 weakened
crust above. As the crust cracks, blocks of rock rise or fall forming
Fault-block mountains. Examples of these mountains are the Sierra Nevada in
California and the Grand Tetons in Wyoming. Dome mountains are formed
by the same kind of molten rock that forms Volcanic mountains. As magma
comes up in a crack in the Earth’s crust, it does not come to the surface, but
the molten rock pushes the ground up into a dome. Examples are Yosemite’s
Half Dome, the Adirondacks in New York, and the Black Hills in South
Dakota.Some mountains started at the bottom of the sea. Scientists found that
out 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 the
bottom of the sea. It is really amazing how mountains are formed by forces
of the earth.