1. The Canadian Shield is U-shaped and is a subsection of the Laurentia craton signifying the area of greatest glacial impact (scraping down to bare rock) creating the thin soils. The Canadian Shield is more than 3.96 billion years old. ... It is the Earth's greatest area of exposed Archean rock.
Unit of: North American craton
Region: North America
Area: 8 000 000 km2
Sub-units: Laurentian Upland; Kazan 2.Rocky Mountains, byname the Rockies, mountain range forming the cordilleran backbone of the great upland system that dominates the western North American continent. Generally, the ranges included in the Rockies stretch from northern Alberta and British Columbia southward to New Mexico, a distance of some 3,000 miles (4,800 km). In places the system is 300 or more miles wide. Limits are mostly arbitrary, especially in the far northwest, where mountain systems such as the Brooks Range of Alaska are sometimes included. The Rockies are bordered on the east by the Great Plains and on the west by the Interior Plateau and Coast Mountains of Canada and the Columbia Plateau and Basin and Range Province of the United States.
Explanation:
