Only about 29 percent of Earth's surface consists of land; the remaining 71 percent is water or ice. Thus, less than one-third of our planet is habitable by human beings, and much of this area is too dry, too cold, or too rugged to allow large concentrations of settlement. Our livable world-where permanent settlement is possible-is small indeed. Each of the six continental landmasses possesses unique physical properties, some of which are listed
Eurasia (covering 36.5 percent of the land surface) is by far the largest landmass on Earth, and all of it lies in the Northern Hemisphere. The topography of Eurasia is dominated by a huge mountain chain that extends from west to east across the giant landmass. The mountains in the chain have many names in various countries, the most familiar of which are the Alps in Central Europe and the Himalayas in South Asia. In Europe, the Alps lie between the densely populated North European Lowland to the north and the subtropical Mediterranean lands to the south. In Asia, the Himalayas form but one of many great mountain ranges that extend from central Asia northeastward into Russia's Siberia, eastward into China, and southeastward into South and Southeast Asia. Between and below these ranges lie several of the world's most densely populated river plains.
Africa, which accounts for just over 20 percent of the Earth's total land area, is at the heart of the land hemisphere. Of all the landmasses, Africa alone lies astride the equator in such a way that large segments of it occupy the Northern as well as the Southern Hemisphere. Africa is called the plateau continent because much of its landmass lies above 1,000 m (3,300 ft) in elevation and coastal plains are relatively narrow. (The word plateau refers to any area of relatively flat high ground.) a long steep slope, or escarpment, rises near the coast in many parts of Africa, leading rapidly up to the plateau surface of the interior. African rivers that rise in the interior plunge over falls and rapids before reaching the coast, limiting their navigability. Africa lacks one physical feature seen on all the other landmasses: a linear mountain range comparable to South America's Andes, North America's Rocky Mountains, Eurasia's Himalayas, or Australia's Great Dividing Range. The reason for this will become clear when the geomorphic history of that continent.
North America comprises one-sixth of the total land area on Earth and is substantially larger than South America. This landmass extends from Arctic to tropical environments. Western North America is mainly mountainous; the great Rocky Mountains stretch from Alaska to Mexico. West of the Rockies lie other major mountain ranges, such as the Sierra Nevada and the Cascades. East of the Rocky Mountains lie extensive plains covering a vast area from Hudson Bay south to the Gulf of Mexico and curving up along the Atlantic seaboard as far north as New York City. Another north–south-trending mountain range, the Appalachians, rises between the coastal and interior lowlands of the East Coast. Thus, the continental topography of North America is somewhat funnel shaped. As a result, air from both polar and tropical areas can penetrate the heart of the continent, without topographic obstruction, from north and south. As a result, summer weather in the middle of North America can be tropical, whereas winter weather can exhibit Arcticlike extremes.
South America, occupying 12 percent of the world's land, is much smaller than Africa. The topography of this landmass is dominated in the west by the gigantic Andes Mountains, which exceed 6,000 m (20,000 ft) in height in many places. East of the mountains, the surface of the continent becomes a plateau interrupted by the basins of major rivers, among which the Amazon is by far the largest. The Andes constitute a formidable barrier to the cross-continental movement of air, which has a major impact on the distribution of South America's climates.
Antarctica, the “frozen continent,” lies almost entirely buried by the world's largest and thickest ice sheet. Beneath the ice, Antarctica (constituting the remaining 9.3 percent of the world's land area) has a varied topography that includes the southernmost link in the Andean mountain chain (the backbone of the Antarctic Peninsula). Currently, very little of this underlying landscape is exposed, but
Antarctica was not always a frigid polar landmass. As we will discuss in more detail in Parts 3 and 4 the Antarctic ice, the air above it, and the waters around it are critically important in the global functioning of the atmosphere, hydrosphere, and biosphere.
Australia is the world's smallest continent (constituting less than 6 percent of the total land area) and topographically its lowest. The Great Dividing Range lies near the continent's eastern coast, and its highest peak reaches a mere 2,217 m (7,316 ft). Australia's northern areas lie in the tropics, but its southern coasts are washed by the outer fringes of Antarctic waters.
Which place is center of Earth?
Earth's core is the very hot, very dense center of our planet. The ball-shaped core lies beneath the cool, brittle crust and the mostly-solid mantle. The core is found about 2,900 kilometers (1,802 miles) below Earth's surface, and has a radius of about 3,485 kilometers (2,165 miles).
Where is the Centre point of Earth?
Sao Tome and Principe is an island nation located in the Gulf of Guinea, off the western coast of Africa, close to the equator. Nicknamed the”centre of the world”,it is the closest landmass to the point in the Atlantic where the imaginary line of the equator crosses the zero meridian.
How old is the world?
4.543 billion years
What is known as a single large landmass?
In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass.
Why is Asia called Asia?
Thus, according to the Akkadian language of Mesopotamia, the land on the eastern side was named ‘Asia,' which means sunrise, and the land on the western side was termed ‘Erebu,' which means sunset. These names instantly gained popularity and spread all across the world.
Who named Asia?
Asia. The word Asia originated from the Ancient Greek word Ἀσία, first attributed to Herodotus (about 440 BCE) in reference to Anatolia or to the Persian Empire, in contrast to Greece and Egypt. It originally was just a name for the east bank of the Aegean Sea, an area known to the Hittites as Assuwa.
Why is Africa called Africa?
Roman theory. According to this school of thought, the Romans discovered a land opposite the Mediterranean and named it after the Berber tribe residing within the Carnage area, presently referred to as Tunisia. The tribe's name was Afri, and the Romans gave the name Africa meaning the land of the Afri.
How many countries are in the world?
Countries in the World: There are 195 countries in the world today. This total comprises 193 countries that are member states of the United Nations and 2 countries that are non-member observer states: the Holy See and the State of Palestine.