Introduction
North America is the third largest continent in the world and has an area of about 24 million sq. km. It was originally inhabited by the Native Americans and Inuit who migrated from Central Europe via the Bering Strait. Though the continent was discovered by Christopher Columbus in 1492 AD, it was named much later after the Italian explorer Amerigo Vespucci who explored North and South America between 1497 and 1502 AD. After the discovery of America, the Europeans started to migrate and settled down in the east coast of the continent and gradually migrated westward. Later, people from Africa came and settled down. Thus, North America is a diversified continent with people of various races, colours and cultures.
Location
North America is located in the western hemisphere. It is separated from Europe by Atlantic Ocean. The vast Pacific Ocean lies between Asia and North America. The continent lies entirely north of the equator. It extends from 7°N to 84°N latitudes. The tropic of Cancer crosses the continent in the south. The Arctic Circle crosses the continent in the north. Most parts of the continent lie in the North Temperate Zone. The continent is separated from Asia by the narrow Bering Strait in the north-west and is linked with South America by the narrow Isthmus of Panama. North America has three large countries Canada, the USA and Mexico.
Physical Features
North America is characterized by clear and well-defined divisions into three physiographic regions. Each region is marked by a certain degree of uniformity in relief, climate, vegetation, soils and other environmental conditions. They are:
a. The Western Mountain System
b. The Central Lowlands
c. The Eastern Highlands
a. The Western Mountain System
The Western Mountain System or the Western Cordilleras are young fold mountains like the Himalayas in our country. These ranges extend from Alaska in the north to the Panama in the south, a distance of about 6,500 km. The width of the mountain region is a maximum of 1,500 km in the middle and decreases towards the north and the south. The western mountain system consists of several mountain ranges running from north to south. The Rocky Mountain Range lies in the eastern margin, the Alaska Range in the north, the Cascade Range in the middle and the Coastal Range in the south. In between the mountain ranges there are plateaus, deep valleys and river basins. Grand Canyon (1,829 m deep), the deepest gorge made by the river Colorado lies here. Similarly, extremely hot and dry valley, the Death Valley lies to the east of Sierra Nevada range in California. The Western Mountain System has many peaks exceeding 4,000 meters above sea level. The highest peak Mt. McKinley (6,190 m) is in Alaska. This region is prone to earthquake and volcanoes. There are many active volcanoes in Mexico and Alaska.
b. The Central Lowland
The Central Plain, also known as the Great Plains, extends from Hudson Bay in the north to the Gulf of Mexico in the south east. This is undulating lowland formed by denudation of land by glaciers and rivers. The northern part around the Hudson Bay is known as the Canadian Shield, which covers a great part of Canada. The Central Plain is drained by river Mississippi and its tributaries. It is the most fertile plain in the world. The extensive temperate grassland known as the Prairies lies in the central plain of North America.
c. The Eastern Highlands
The Eastern Highlands are old fold mountains which have been denuded over millions of years. The ranges do not exceed 2,100 m in altitude. The eastern highlands are lower than the western mountains. It is formed by three important highlands, the Plateau of Greenland, the Canadian Shield covering a great part of Canada to the north of the St. Lawrence River and the Appalachian highland. The Appalachian highland lies to the south of the St. Lawrence River in the south east of the continent. To the east of the highland lies the Atlantic coastal plain.
Rivers and Lakes
The Mississippi is the most important river of North America. The Missouri River and Arkansas River are its tributaries which join River Mississippi and drains into the Gulf of Mexico. Rivers like the Nelson, the Mackenzie drain into the Arctic Ocean, the Yukon, the Fraser, the Columbia and the Colorado drain into the Pacific Ocean, while, the river St. Lawrence drains into the Atlantic Ocean. St. Lawrence is the busiest river in terms of trade and business. Most of the rivers drain towards the east of the continents. They have created extremely fertile plains. There are five important lakes in North America. They are Lake Superior, Huron, Erie, Ontario, and Michigan known as the Great Lake lying at the border of Canada and the USA. The famous Niagara Falls is located between Lake Erie and Ontario.
Climate
The continent of North America experiences a variety of climate due to its vast latitudinal extent, varied relief features, impact of ocean currents and prevailing winds. North America lies in a wide belt of temperate region. It also includes the Tropical and Tundra climate in the south and north respectively. The northernmost part of the continent is extremely cold throughout the year. Western coast of Canada and north western part of the USA has a mild climate. The central part of the continent has an extreme climate. It is very hot in summer and very cold in winter. The eastern part of Canada and the areas around St. Lawrence River receives rainfall throughout the year. California and Florida receive rainfall only in winter. The south east part of the USA is under the influence of cyclones and receives rainfall in summer. The southernmost part of the continent is hot and wet throughout the year. South-west part of the USA has the desert climate.
Natural Vegetation
The natural vegetation largely depends on climate, soil and relief features. Due to great diversity in climate and relief, North America has a wide variety of vegetation. These vegetation belts broadly follow the climatic zones. It has tundra type of vegetation and coniferous forests in the northernmost part of Canada. This region is severely cold with short summers and that is why some quick flowering plants, bushes and coniferous trees are found here. The central part of the country has extensive temperate grassland called Prairies. This region receives low amount of rainfall and thus there is no thick growth of vegetation. Tall trees are absent and only grass grow here, which is the main vegetation. The areas around the St. Lawrence River and south east of the USA have mixed temperate forest comprising of coniferous and deciduous trees. Some important trees of these forests are oak, beech and maple.