(56).Continent-continent convenient plate boundary.

What do you see at a continent-continent convergent plate boundary?

Nowhere along the west coast of North America is there a convergent plate boundary of this type at this time. Why are there no continent-continent convergent boundaries in western North America? The best place to see two continental plates converging is in the Himalaya Mountains, the mountains that are the highest above sea level on Earth.

Continent-Continent Convergence

Continental plates are too buoyant to subduct. What happens to continental material when it collides? It has nowhere to go but up!

[Figure 1]

A diagram of two sections of continental crust converging.

Continent-continent convergence creates some of the world’s largest mountains ranges. Magma cannot penetrate this thick crust, so there are no volcanoes, although the magma stays in the crust. Metamorphic rocks are common because of the stress the continental crust experiences. With enormous slabs of crust smashing together, continent-continent collisions bring on numerous and large earthquakes.

A short animation of the Indian Plate colliding with the Eurasian Plate: http://www.scotese.com/indianim.htm.

An animation of the Himalayas rising: http://www.youtube.com/watch?v=ep2_axAA9Mw.

The Appalachian Mountains along the eastern United States are the remnants of a large mountain range that was created when North America rammed into Eurasia about 250 million years ago. This was part of the formation of Pangaea.

Summary

Continental crust is too buoyant to subduct. If the two plates that meet at a convergent plate boundary both consist of continental crust, they will smash together and push upwards to create mountains.

Large slabs of lithosphere smashing together create large earthquakes.

The activity at continent-continent convergences does not take place in the mantle, so there is no melting and therefore no volcanism.

The amazing Himalaya Mountains are the result of this type of convergent plate boundary.

Old mountain ranges, such as the Appalachian Mountains, resulted from ancient convergence when Pangaea came together.