This edge, heavily populated with volcanoes, is called a continental arc. The volcanic mountains on the plate border described above can run into a continent, shatter the collision
area and stack up the pieces into a mountain range. This is how the Appalachians were formed.
When a continent-sized "layer cake" of rock is pushed, the upper layers move more readily than the lower layers. The layers separate from each other, and the upper few miles of rock move on ahead, floating on fluid pressure between the upper and lower sections of the crust like a fully loaded tractor trailer gliding effortlessly along an icy road. The flat surface where moving layers of crust slide along the top of the layers beneath it is called a thrust fault, and the mountains that are heaved up where the thrust fault reaches the surface are one kind of fault block mountains. The mountains of Glacier National Park slid along the Lewis thrust fault over younger rocks, and out onto the Great Plains.
Mountain ranges start being torn down by physical and chemical forces while they are still rising.
This is a free page. This page contains 181 words. This
article contains 3,646 words (approx. 12 pages at 300
words per page).
Read the rest of this Article with our North America Access Pass.
