The entire surface of the Earth is made up of water and land. Moreover, the solid part accounts for only 29% of the total area of the planet. Yes, and that is indented by rivers, streams, streams, canals. And how many swamps, ponds and lakes there are on land - one cannot count, since some of them periodically disappear, then reappear. Probably, it would be more correct to call our planet Water.
All land is divided into separate continents. They are also called continents. What is the mainland, what is the history of its origin and development - for a long time remained a mystery. Today, geological science can explain many things, in particular, why the continents move.
What are they made of
A huge granite-sedimentary block lying on a bas alt layer, about 40 kilometers thick - that's what a mainland is. Today there are six continents, and they are located on the earth's surface very unevenly, grouped in the opposite part of the planet from the Pacific Ocean. Continents are heterogeneous in their structure. They consist of:
- geosynclines (folding areas);
- platforms (sustainable areas).
Answering the question of what a continent is, we can say that it is a large landmass washed by the ocean and consisting of mobile and stable sections.
The moving parts of the continents are folded zones, stretched in length for thousands or even tens of thousands of kilometers. An example of such a geosynclinal region is the Alpine-Himalayan belt, which stretches in a latitudinal direction across the whole of Eurasia. In the relief, folding is expressed by mountains and depressions.
Platforms are slow moving areas. These are stable, long-formed parts of the earth's crust. They are covered from above with a cover of sedimentary rocks, which hide all the irregularities of the foundation. Large plains are located on such areas of the earth's crust. An example is the East European Plain, which is located on the Russian platform.
Continental drift
In our time, there are 6 continents. The largest of them is Eurasia, and then they are located in this order: Africa, North America, South America, Antarctica and the smallest - Australia.
But there was a period in the history of the Earth when there was only one supercontinent Pangea and it was washed by the waters of one ocean Panthalassa. What is a Mesozoic continent? This is a huge landmass, equal in size to all of today's continents combined. Pangea was covered with lush vegetation, among which dinosaurs roamed freely. This was their kingdom and their heyday.
Approximately 200 million years ago, the ancient continent split into Laurasia and Gondwana. The Tethys Ocean formed between them. Laurasia went to the northern hemisphere, while Gondwana remained in the southern.
In turn, these two ancient continents, under the influence of the movement of the mantle substance, also split into separate parts, which began to drift in different directions, gradually moving away from each other. This is how modern continents were formed, the outlines of which we know from school.
Thus, any modern continent is just a fragment of ancient Pangea that existed in the distant past.
