Geoscience Reference
In-Depth Information
Figure 20.4. Major physiographic regions of North America.
and Basin and Range Province in the south. The central lowlands are made up of the
Laurentian or Canadian Shield to the north, the Great Plains and the Central Lowland
to the south, and the Gulf and Atlantic Coastal Plain in the far south. The eastern
hills include the Appalachians in the west, the Piedmont region in the south and the
isolated Ozarks to the east. The deserts and drier areas coincide very broadly with the
Colorado Plateau, the Basin and Range Province, and the Great Plains.
The Rocky Mountains are the single most important physiographic feature in North
America in terms of their effect on climate. They extend for 5,000 km from the tropics
to the subarctic and are aligned north-south, perpendicular to the dominant westerly
winds. Although not as high as the mountains of Asia or the Andes, the Rockies are
high enough to have a permanent cover of snow in the north, where they reach a
maximum elevation of 6,196 m (20,320 feet) on Mount McKinley in Alaska. Two
