Lithosphere

A lithosphere is the rigid, outermost shell on Earth. It is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater. The outermost shell of a rocky planet, the crust, is defined on the basis of its chemistry and mineralogy.

Lithosphere

This includes the crust and the uppermost mantle, which constitute the hard and rigid outer layer of the Earth. The uppermost part of the lithosphere that chemically reacts to the atmosphere, hydrosphere and biosphere through the soil forming process is called the pedosphere.

Lithosphere composition

The earth’s crust is not a homogeneous substance, it has different layers of rocks including sedimentary rocks on top, granitic and metamorphic rocks in the middle and basaltic rocks on the bottom.

The earth’s crust also consists of several large dynamic tectonic plates. These tectonic plates moves slowly but continuously at an average rate of around 10 cm. Considering this, there was no Atlantic Ocean, and North America and Europe together were one continent 180 million years ago. The Atlantic Ocean came into being because of the drafting apart of the Eurasian and North America plates.

Types of Lithosphere

These are two types:

Oceanic,which is associated with oceanic crust and exists in the ocean basins.

Continental,which is associated with continental crust.


Practise This Question

Which among the following is a  transverse wave?