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Topography and Tectonics
Why are some mountains very high, such
as those in the Himalayas, while others--like the Appalachians--are much lower?
Mountains and all areas of high topography need to be maintained by some sort
of dynamic process. If not they will eventually erode and become flat plains.
The existence of regions of high topography tells us that some sort of tectonic
process must be operating, even if we cannot observe it directly.
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| Left:Location of Himalayan cross-section
drawn in red on top of topography. Right: Cross-sectional view of the Himalayas. |
In the Himalayan Mountains of Asia, two of the Earth's tectonic plates are converging. The Indian plate is moving northward and colliding with the Asian plate. Because both India and Asia are made of continental crust, which is thick and low-density, the plates buckle and bend, creating a thick and deformed region of continent. This deformation is seen at the surface as the high peaks of the Himalayas. The collision is accompanied by many earthquakes. Additionally, the high topography above the surface is mirrored in the subsurface by a "crustal root," a region of thick crust extending down into the mantle, just as the high mountains extend upward into the atmosphere.
Discovery Topics > Topography > Topography and Tectonics <
