As a consequence of these disruptions, the oceans also suffered division, obeying the transformations caused by the masses of the new continents.
This gave rise to another theory called Plate Tectonics.
Plate tectonics is a theory originated from continental drift and ocean floor expansion. It was developed in 1960, and has become the most accepted among geographers and oceanographers.
According to this theory, the lithosphere moves over the asthenosphere. The lithosphere is in turn divided by plates (called tectonic plates) and they slide because of convection currents within the Earth. The heat that comes from the core of the earth warms the mantle and makes the warmer parts rise. These parts cool and fall back down. It is these currents that slowly move the plates that form the earth's crust.
The movement of one plate relative to another is about 2 to 10 cm per year. Therefore it is practically not perceived by our senses. Over millions of years, however, this movement has greatly changed the appearance of our planet, moving some continents away and bringing others closer.
Such movements allowed the formation of continents from Pangeia, a continent that existed 200 million years ago during the Mesozoic era.
- Ocean plate is the name that designates the plates that are submerged by the oceans, while continental plate is the name given to designate the plates located under the continents.
There are several tectonic plates of different sizes, but the most important are:
- African plate: It covers the entire continent of Africa and through its collision with the Eurasian plate came the Mediterranean Sea and the Rift Valley.
- Antarctic Plate: It covers all of Antarctica and the southern oceans.
- Eurasian plate: It covers the European and Asian continent, except India, Arabia and part of Siberia. Includes the eastern part of the north Atlantic Ocean.
- North American Plate: It covers North America, western part of the northern Atlantic Ocean, part of the Arctic Glacial Ocean and part of Siberia.
- South American Plate: It covers South America and the east of the Atlantic Ocean Crest.
- Pacific plate: It covers most of the Pacific Ocean and through its collision with the Antarctic Plate came the Pacific-Antarctic Plate.
- Indo-Australian Sign: Covers Australian Plate and Indian Plate. It also covers much of the Indian Ocean and part of the Himalayas.