Fig. 46 Mountain building

Date: 2015-10-07; view: 560.

Mountain building is a complex process. Deep troughs of accumulated offshore sediment, volcanic rocks, bits of oceanic crust, and scraps of foreign continents can all be swept against one continent and welded on as mountain ranges. Most of mountainous western North America consists of more than 50 suspect terranes – mighty slabs of alien rock that independently rotated and migrated north along the western edge of North America.

Here are three major mountain-building processes.

1. Oceanic plate subduction below another oceanic plate – this process created the Aleutian Islands and other mountainous island arcs.