The Earth has 15 major tectonic plates, with seven or eight primary plates and the rest secondary. Tertiary plates are smaller parts of primary or secondary plates. The theory of plate tectonics explains that these plates float on the asthenosphere and move over millions of years, causing geological formations and earthquakes. The movement can be divergent, convergent, or parallel along their boundary. The largest primary plates are the Antarctic Plate, Eurasian Plate, and North American Plate.
The Earth is generally believed to have 15 major tectonic plates, seven or eight of which are primary plates and the rest are smaller secondary plates. The primary plates are the African Plate, Antarctic Plate, Eurasian Plate, Indo-Australian Plate, North American Plate, Pacific Plate, and South American Plate, with the Nazca Plate sometimes considered a primary plate rather than a secondary plate . The secondary dishes are the Arabian dish, the Caribbean dish, the Cocos dish, the Indian dish, the Juan de Fuca dish, the Philippine Sea dish, the Scotland dish, and sometimes the Nazca dish. Additionally, there are dozens of minor and tertiary plates. Just as there’s no consensus on whether the Nazca Plate is a primary or secondary plate, there’s no agreement on how many tertiary plates there are, but scientists have identified about 58 of them.
Theory of plate tectonics
Tectonic plates are large plates of rock that form the top layer of the Earth, called the lithosphere. Both continents and oceans rest on tectonic plates, which float on the asthenosphere, the superheated molten rock underneath. Scientists believe that over millions of years these tectonic plates float around, pushed by convective currents in the asthenosphere, gathering into supercontinents and dispersing again. This is called the theory of plate tectonics. The tectonic plates move at the same rate as a person’s fingernails grow, 2 to 4 cm a year.
Primary dishes
Although primary plates often share names with continents or oceans, their boundaries simply don’t correspond to those areas. For example, the North American Plate includes Greenland, which is generally associated with Europe. Each of the primary plates also includes areas under one or more oceans. The largest primary plates are the Antarctic Plate, the Eurasian Plate and the North American Plate. The Pacific Plate includes most of the Pacific Ocean and part of Southern California.
Secondary and tertiary dishes
Some scientists classify primary plates and secondary plates under the term “major plates.” Of the plates typically classified as minor plates, the Arabian Plate and the Indian Plate comprise the largest areas of land. Tertiary plaques are smaller parts of primary or secondary plaques that have ruptured and are being ruptured over time. These are often grouped with the associated primary or secondary plates.
Movement along plate boundaries
As adjacent plates move, they may move away from each other, toward each other, or in parallel directions along their boundary. This movement can cause an earthquake and create a geological formation. When plates move away from each other, called divergent motion, they can create rift valleys on land. In the ocean or sea, they can create volcanic ridges or islands, which occur when the spreading seafloor provides an opening for molten lava to rise up from the land.
Convergent motion is when plates move towards each other. When the plates collide, one might be forced under the other, or both might be pushed up. Two plates converging under the ocean can cause islands to form. An oceanic plate colliding with a continental plate can form mountains near the coast. Two continental plates colliding can form a mountain range, such as the Indian plate and the Eurasian plate forming the Himalayas.
Adjacent plates sometimes move in parallel directions along their boundary, which is called a strike-slip fault. For example, the Pacific Plate moves north as the adjacent North American Plate moves south along the San Andreas Fault in California. While movement along fault lines like the San Andreas doesn’t create formations like mountains or valleys, it does cause frequent earthquakes.
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