Land of the planet Earth: area, continents, oceans and interesting facts
What is land? This is the part of the earth's surface that water bodies do not hide under themselves, starting from the world ocean and ending with lakes, rivers and reservoirs. Thus, under the land can be understood any part of the mainland or island, not flooded with water.
What is the percentage of the land mass of our planet? Slightly less than a third of it is given to forests (about 27%), even less (21%) - to natural pastures, a little less than 10% is used for arable land and as much for irrationally used land.
Another 11% are deserts and glaciers. Most of the latter lies, as it is easy to guess, in Antarctica. Cities occupy no more than 1% of the total land mass of the Earth.
How much is the land area on Earth according to scientists? The overwhelming amount of the surface of our native planet is reserved for the water space, called the oceans.And only 29% of it is occupied by continents, which in numerical terms equals approximately 149 million square kilometers. At the heart of them lies the crust, its thickness varies in different places from 25 kilometers and more. Modern geography recognizes the mainland 6 main and largest areas, which are divided land on the planet Earth: Africa, Eurasia, South and North America, as well as relatively small Australia and Antarctica.
Who is bigger?
The supremacy in size, as is known from the school course of geography, belongs to Eurasia, stretching from its bizarrely broken coastline from Cape Roka in the west to Cape Dezhnev in the east for all 16,000 kilometers. Its territory is more than 50 million square meters. km And this is the only continent, standing on the coast of which, you can admire the view of one of any four world oceans.
The second place in the rating of “The Biggest Land on the Planet” is Africa, which is confidently holding. Its middle line (about half the distance between the extreme northern and southern points) is located almost exactly at the equator. From the north, the mainland is connected with the aforementioned Eurasian champion only by a narrow Suez Isthmus.
In third place is North America. It lies completely in the northern hemisphere and occupies just over 24 million square meters. km from the territory that represents the entire land of the planet. Three oceans (Atlantic, Pacific and Arctic) wash its shores. The Bering Strait, which serves as the natural border between it and Eurasia, as scientists think, was not in the deepest antiquity: in its place was the isthmus, which connected the continents.
Other America (South) is spread mainly in tropical and equatorial latitudes. Its coastline is less indented, and the area washed by the waters of the Atlantic and Pacific Oceans (and from the north, the Caribbean) of the continent, together with all the islands, is about 17.8 million square meters. kilometers This is the fourth largest land of the planet.
Who is the outsider in this ranking? The smallest of the continents - Australia (only 7.6 million square kilometers.). Its territory is located completely below the line of the equator. There are no land connections between this small green continent and the rest, from which Australia is significantly removed.
Antarctica is held somewhat apart among fellow continents.It is the most sparsely populated of all the parts into which the land of the planet is divided. And it is not surprising, because its entire territory (which is about 14 million square kilometers) lies completely below the Southern Arctic Circle, and the geographical center of the continent practically falls to the South Pole. The entire area of the mainland is completely hidden under an impassable layer of ice and snow.
Planet Earth: land and water
And what do we know about the oceans? Of the 4 water giants that our planet possesses, leadership in size and depth, of course, belongs to Silent. The total volume of it is over 1300 million cubic kilometers, and the area with all the seas is more than 170 million square meters. km If its average depth is about 4,000 meters, then the maximum depth is more than 11,000 meters. On the territory of it is also the largest accumulation of islands.
The smallest of the oceans is the Arctic Ocean, with only 4% of the water surface of the Earth set aside for it. It is 3 times less than the other three giant oceans. In addition, it is the most difficult to access. This is due to the multi-year ice layer more than 4 meters thick. Through it, a path called the Northern Sea Route has been laid; it can be reached from the European part of our native country to the Far East.
Terrestrial land: the formation of continents
Since school, each of us knows in detail the outlines of the continents and the largest islands. But they were not always like that. Scientists have long proven that the lithosphere of the Earth is made up of tectonic plates, the lot of which is to move along the mantle lying under them.
The age of our globe, according to scientists, is approximately equal to four and a half billion years. Already in the Archean era (the oldest in Earth history), the Earth consisted of oceans and continents, the outlines of which, however, were far from modern. And then, and in our days, the continental crust was formed and formed from rocks melted in the depths of the earth's interior and brought to the surface.
What the contours of the Earth depend on
The entire lithosphere is represented by tectonic plates capable of converging, diverging and mutually colliding. During these clashes, any of them can go deep into, plunging under the next. In areas of such dives, active volcanoes and deep ditches are formed.
In the same place where there is a discrepancy between the plates, the crust crosses deep cracks. The rocks melt to form basalt, which rise up, filling these cracks, and harden in the upper layers of the Earth's crust.In place of the ocean, when the plates diverge, an ocean floor forms with underwater ridges.
In the past, most of the modern southern continents existed together in the form of a giant continent, called the scientists of Gondwana. The connection of the ancient continents occurred during the Paleozoic era, the beginning of which falls on the time mark about half a billion years ago, and lasted for about 300 million years.
At the end of this period, the movement of tectonic plates led to the connection of Gondwana with other continents. The result was a huge land, which united almost all the ancient continents.
The name of this single continent, scientists, geologists gave - it was Pangea, it was located from the North to the South Pole. The mountain systems that now exist in North America, Asia, Australia are the result of the convergence of tectonic plates.
The division of the single continent of Pangea into separate continents began hundreds of millions of years later. As a result, the land of the planet (continent) and the oceans, with their outlines, gradually came close to those we used to observe on modern geographical maps.
For many years, geologists have doubted the plausibility of the theory of continental drift, that is, the ability of the continents to come closer and move away. But scientific data collected in the sixties of the last century dispelled these doubts.
Why is this so?
The outer earth envelope (lithosphere), being solid and extending inland to a hundred kilometers, consists of tectonic plates. These plates can move because in the depths of the lithosphere the Earth's mantle is a much more liquid high temperature substance that supplies energy for the movement of tectonic plates.
Now the number of large and medium lithospheric plates is about 10. These include Eurasian, African, Pacific and others. They move at a speed of several centimeters annually. This is how the process of separation of America, Europe and Africa began about 180 million years ago. At the same time between them formed the ocean, now called the Atlantic.
Looking at the modern map of the world, you can see that the coastal contours of the continents, separated by the Atlantic Ocean, coincide quite accurately. Of course, such a coincidence is not the only argument in favor of the continental divergence theory.Scientists have collected evidence using the latest scientific research in the field of geology and oceanography.