North America: position, relief, climate and waters

North America lies in the Northern and Western hemispheres and is third in area after Eurasia and Africa. Three oceans wash it; it joins South America through the Isthmus of Panama (narrowest about 50 km) and is separated from Eurasia by the Bering Strait (about 85 km). It has the world’s largest island (Greenland, over 2.1 million km²) and largest archipelago (the Canadian Arctic Archipelago). At the end of the 10th century the Norseman Erik the Red explored Greenland and in 1497 John Cabot reached Newfoundland; in the 18th century Russians explored Alaska, which was sold to the USA in 1867. North America was once part of Laurasia together with Eurasia, then split away. The eastern part corresponds to an ancient platform: plains of sedimentary rock and shields of hard igneous rock. In the west the young Cordillera rose; it is part of the Pacific “Ring of Fire”, with frequent earthquakes and volcanoes. In the east are the very old, worn-down, low Appalachians (Mount Mitchell, 2 037 m). The highest point is Denali in Alaska at 6 190 m (called McKinley until 2015; the book gives 6 194 m, and newer surveys give 6 190 m); the lowest is Death Valley (–86 m). The Colorado River has cut the Grand Canyon (446 km long, up to 1.8 km deep). Iron, copper, nickel, uranium and gold lie in mountains and shields; oil, gas, coal and salt in the sedimentary layers.