Download How Are Landforms Shaped

How Are Landforms Built?
The earth's surface is built of material that comes from beneath the crust, or it is formed by the movement
of the crust itself.
The heat of the earth's interior creates convection currents in the mantle.
These convection currents sometimes cause the magma in the mantle to break through the crust of the
Earth as lava and volcanic ash.
At other times, moving magma may cause the plates to separate or collide at their boundaries, resulting
in parts of the crust moving upward to create block mountains, or downward to produce trenches and
rift valleys.
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How Are Landforms Shaped?
Canada's topography is the result of four forces:
 the building-up forces of mountain building- When the continental plates collide, they can push up
mountains. When undersea plates collide, the plate edges are pulled down in a subduction zone, and deep
trenches and valleys are produced.
 the wearing-down forces of weathering, or exposure to the atmosphere-the gradual breaking down of
solid rock by exposure to air, water, animals, and plants.
 the wearing-down forces of erosion- the process by which the land surface is sculpted and the
weathered particles are carried away, or transported, by running water, tides, wind, and glaciers
 the building-up forces of deposition, where eroded materials add new shapes-the depositing of
the weathered particles as sediment by the agents of erosion.
There are four types of mountains:
Volcanic and dome mountains are formed by rising magma beneath the earth's crust.
Fold mountains and fault block mountains and the Mid-Atlantic Ridge are formed by the
movement of the plates.
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