The North American Craton (brown) has comprised a portion of a series of supercontinents, and has remained stable for about 600 million years. This cratonic region comprises a basement of Precambrian metamorphic and igneous rock, exposed in the north as the Canadian Shield, and covered by a relatively thin cover of younger sedimentary rock on the Interior Platform.
The geologically stable rocks of the cratonic core are surrounded by deformed rocks (purple) and more recently deposited sedimentary material (green). Compare to bedrock of North America.
Maps of North American rock types : rock types - metamorphic, plutonic, sedimentary, volcanic; tapestry of time and terrain, terrain.