Structure and Composition of the Earth

Geophysics is a branch of science that deals with the physical, chemical, geological, astronomical and other characteristic properties of the earth. It deals with geological phenomena such as the temperature distribution of the earth's interior, the source, configuration and the geomagnetic field.

Structure and composition of the earth

The structure of the earth is composed of three major zones arranged in concentric manner.

These are

1. Crust
2. Mantle

The crust

Is the outer solid layer of the earth.

There are two types of crust, namely:

1. Continental crust: This is heterogeneous and of relatively low density. It is composed mainly of granites and sedimentary rocks.
2. Oceanic crust: This is basaltic and denser. Both the continental and the oceanic crusts floats on the denser mantle. Because of its low density, the continental crust floats on the mantle at a higher elevation, forming the landmasses and mountains.

The mantle

It begins from the Moho and extends to a depth of 2,900km below the earth's surface, up to its boundary with the earth's core. This boundary is called the Gutenberg discontinuity.

The core

Is the innermost part of the earth. It extends from the Gutenberg discontinuity to the earth's geometric center.

The core consists of two distinct regions namely:

1. The inner core: It is composed of solid material because the high pressure at this depth.-It is composed of iron-nickel alloys.
2. The outer core: Is composed of liquid of molten nickel and iron known as magma.

The composition of the layers of the earth

Continental crust is made of granite and sedimentary rocks forming the lands and the mountains while the oceanic crust forms oceanic basins. Mantle is made of solids and molten rocks. The outer core is made of molten nickel and iron called magma while the inner core is solid because of the high pressure.

The importance of the layers of the earth

Continental crust forms the land and mountains of the earth on which all human activities are carried out e.g farming, housing etc. Oceanic crust forms the base of the oceans and seas on which oceanic water rests and all aquatic organisms like fishes live. The mantle provides the heat transfer from the core to the outer layers a process, which causes the volcanic actions and earthquakes.