According to Countryaah, North America can be divided into a few geomorphological large regions: the geologically oldest part is the Canadian Shield, a mainland core that occupies large parts of the northeast around Hudson Bay; the relief is undulating with rocks and hollow shapes. Its rock continues to the west and south in the depths, but is overlaid here by powerful sediments, the surface of which is relatively flat. These include the Central Lowlands around the Great Lakes as the deepest part of the Interior Plains, which extend from the coastal plain on the Gulf of Mexico to the Arctic Ocean. To the east, the Appalachian Mountains are 2,600 km long, an eroded rump mountain range with plateaus and ridges that rise in Mount Mitchell in the south to 2,037 m above sea level. In the west, the geologically younger Cordilleras stretch through the continent with a maximum width of 1,500 km in a north-south direction. They are divided into longitudinal zones in the Rocky Mountains in the east with heights of 3,000-4,000 m above sea level, in a series of intermontane plateaus (including Yukon and Columbiaplateau, Great Basin, Colorado Plateau) and in the Pacific coastal chains, which in of the Alaska range in Denali can reach 6,198 m above sea level. Numerous earthquakes in California and Alaska as well as volcanism (1980 eruption of Mount Saint Helens in the Cascade Range in Washington State) testify to the instability of the mountain area. The chain of the Rocky Mountains is the main watershed, so only about a quarter of the land is drained to the Pacific. a. through the Yukon River, Fraser, Columbia River and Colorado River. The largest rivers in North America, Mississippi with Missouri, Saint Lawrence River and Mackenzie, belong to the catchment area of the Atlantic.
The North America is particularly rich in lakes; the largest contiguous freshwater surface on earth are the five Great Lakes (Lake Superior, Lake Huron, Lake Michigan, Lake Erie and Lake Ontario). Like most lakes, they were formed by glaciers in the last ice age. The inland ice cover covered v. a. Canada, in the area of the Great Lakes, it bulged further south and reached on the Atlantic coast up to the height of New York. Glacial formation of the mountains and deposits are widespread in this area, as are strongly indented coasts with fjords and bays. In the south, on the other hand, there are lagoon and spit coasts with extensive swamps in the hinterland.
Climate
Most of North America has a pronounced continental climate with high temperature contrasts, only the coastal areas are more balanced. North America is in the area of the westerly wind zone, but most of the Pacific ocean air masses rain down in the windward high mountains (on the west coast of the northern USA and Canada with precipitation of over 2,000 mm annually). To the east there are extensive dry areas in the rain shadow, in the Great Plains (approximately west of 100 ° west longitude) with annual rainfall of less than 500 mm, in the intermontane basins, especially in the southwest, extremely arid deserts. To the east, precipitation increases to over 1,500 mm. The temperature zones are from north to south: arctic and sub-arctic zones with only two to three frost-free months a year; the extensive cool or warm temperate zones; in the south the subtropical and only at the tip of Florida the tropical zone. The south-east is under the influence of tropical air masses with hot summers, mild winters and high humidity, and there are frequent hurricanes that cause destruction, especially in the coastal area.
Since there are no west-east mountain barriers, polar cold air can penetrate unhindered to the south (Blizzard, Northers) or subtropical warm air to the north. Tornadoes occur frequently east of the Rocky Mountains (around 1,000 per year).
Flora
The flora of North America is part of the Holarctic. Apart from the ice desert, the entire north beyond the Arctic Circle is characterized by tundras (lichen, dwarf shrub, tree tundra) with numerous circumpolar species (e.g. dwarf birch). Boreal coniferous forest joins to the south, in which v. a. Larchs and various species of fir, spruce and pine dominate. The northern Cordilleras are v. a. overgrown with hemlocks, Douglas firs, arborvitae, false cypresses and junipers. The coastal redwood (Sequoia; southern Oregon to northern California) and the sequoia (Sequoiadendron; western Sierra Nevada) colonize only a very limited area. There are evergreen hardwood trees (chaparral). In the rest of the area south of the 44th parallel, the lower mountain level is overgrown with pine and juniper forests. The uppermost forest zone in the central Rocky Mountains from 2,500–3,700 m above sea level is formed by spruce and fir forests. Above it there is an alpine region with meadows and rock corridors. The Atlantic flora area includes deciduous forests in the eastern part, which become evergreen in the south and expansive grassy areas to the west (prairie) skip. At about 37 ° north latitude, there are salt deserts with little vegetation. The Pacific flora area becomes drier and drier towards the south and turns into a thorn bush formation (»mesquite«) and finally into semi-desert. At this point, at the latest, an intimate connection with neotropical geo-elements begins, which is also evident from the increased occurrence of cacti, bromeliads and representatives of the genus Yucca. The southern parts of Florida already belong to the Neotropics.
Wildlife
The animal world of North America mainly belongs to the Nearctic and has similarities with the European animal world: z. B. Reindeer (caribou), marmot, beaver, mole, salamander, pike. While the land connection was temporarily missing (in the Tertiary), there was also an intensive exchange of fauna with South America (e.g. armadillos, opossums, hummingbirds). The arctic circumpolar species polar bear, musk ox, ptarmigan and snowy owl live in the far north. The boreal coniferous forest is home to lynx, wolverine, wolf (timber wolf), elk, elk, and skunk. Black (baribal) and brown bears (subspecies: Kodiak and grizzly bears) also live here. The prairies are characterized by bison, coyote, prairie dog and pronghorn (which was heavily decimated after the colonization by the Europeans).