Geology of the United States of America

The overall geology of the U.S.A. is a convergent plate rim in the west, which runs north to sout and causes an orogeny, which is responsible for the Rocky Mountains. This plate rim is also the source of volcanism, most famous is probably the eruption of Mt. St Helen. The mountain ridge along the east coast is not active any more, the mountains are eroded and mostly there is hill country. The center has plains, which are more or less a result of the huge rivers. Caves can be found in the mountains and hills when the rock is limestone or marble. The plains are not suitable for caves, even if an area is karstified, the water table is very close to the surface and so caves are waterfilled. However, the geology on the scale of the whole country is rather complicated, so check out the pages of the States for regional geology.