Question

What are tectonic plates?

Answer 1

Hint: These structures form the ocean beds and the continents of the world. Their movements are responsible for causing earthquakes. They together form the entire lithosphere of the earth. The theory and study of their movements and how it affects the earth as a whole are called ‘plate tectonics’.

Complete answer:
The Earth is made of concentric shells of rocks, minerals and metals. These are the core, the mantle and the crust. The core is the innermost region of the earth and the crust is the outermost shell. The crust is the rock layer on which the biosphere exists. The crust of the earth is completely made of rocks and hence it is called the lithosphere.

The lithosphere is broken into several rocky plates which are called tectonic plates. They form the continents and the beds of the oceans. They are called continental and oceanic plates respectively. The oceanic plates are composed of silicon and magnesium. The continental plates on the other hand are composed of silicon and aluminum.

There are seven major and numerous minor and micro tectonic plates in the earth’s crust.
The seven major plates are;
i) African Plate – It underlies the part of Africa which is to the west of the East African rift
ii) Antarctic Plate – It contains the continent of Antarctica
iii) Eurasian Plate – It contains Europe and most part of Asia
Indo-Australian Plate – Formed from the fusion of Indian Plate (minor plate) and the Australian plate (major)
iv) North American Plate – It contains North America, Greenland and Siberia.
v) Pacific Plate – It is the largest plate and underlies the entire Pacific Ocean.
vi) South American Plate – Contains South America and parts of the South Atlantic Ocean.

Note: Tectonic plates whose areas are less than 20 million square kilometers and more than 1 million square kilometers are considered minor plates. Any tectonic plate whose area is less than 1 million square kilometers is categorized as microplates. These plates are generally not seen on maps or globes as they are too small to be marked on them.