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INTERNAL STRUCTURE OF THE EARTH
Transcript of INTERNAL STRUCTURE OF THE EARTH
The structures of the Earth are quite easy to understand. It has 3 main parts. There is the CORE, the MANTLE and the CRUST.
WHAT ARE THE INTERNAL STRUCTURES OF THE EARTH?
A QUICK RECAP...
WHAT IS THE CORE?
The Earth's core is divided into 2 parts:-
The outer core
The inner core
The outer core of the Earth is a liquid layer about 2266 kms thick. It is mainly made from iron and nickel and has small amounts of oxygen and sillicon. It is located above the Earth's inner core and below the mantle.
The inner core of the Earth is a solid sphere about 1216 kms in radius or 70% of the moon. It is an iron-nickel alloy having similar temperatures to the Sun (5505°C).
WHAT IS THE MANTLE?
The mantle is one of the 3 main layers of the Earth. It lies between the innermost layer core and the outermost thin layer crust. The mantle consists of hot, dense, semisolid rock and is about 2900 kms thick. The mantle itself consists of several layers. Some if them are the lithosphere, asthenosphere, upper mantle and lower mantle.
The lithosphere is the thin outermost shell of the upper mantle. It is similar to the crust though it is cooler and more rigid.
The lithosphere is broken down into several large pieces/plates. They float on a softer mantle layer called the asthenosphere.
The upper mantle lies below the asthenosphere. It is more stronger and solid than the asthenosphere.
The rest of the mantle between the upper mantle and the core is known as the lower mantle. It is denser and hotter that the upper mantle.
WHAT IS THE CRUST?
The Earth's crust is like the skin of the apple. It is very thin in comparison to the other 3 layers. The crust of the Earth, just like the lithosphere, breaks down into pieces called plates. These plates float on the soft mantle which is located below the crust. Most of the times the plates float smoothly but sometimes they stick and build up pressure. The pressure keeps building and the rock starts bending and snaps. This is when an Earthquake occurs.
BENEFITS OF THE CORE
The inner core is thought to rotate at a different speed than the rest of the Earth. This is then thought to contribute to the Earth magnetic field. The inner core makes an extra rotation every 700-1000 years compared to the surface.
Without the outer core life on Earth would be very different. Many scientists believe that the convection of liquid metals in the outer core creates the Earth's magnetic field. This magnetic field extends outward from the Earth for several thousands of kms creating a protective bubble around the planet deflecting the Sun's solar wind. Without this field the solar wind would have blasted away the atmosphere on the Earth leaving it as lifeless as Mars.
BENEFITS OF THE MANTLE
Although much less of the mantle is known compared to the crust, everything that we do know comes from the study of seismology.
The upper mantle contains rocks that are rich in magnesium and iron. The upper mantle and lower mantle make up to 51% of Earth's mass.
BENEFITS OF THE CRUST
The crust is where we live on. It is the home of life. The Earth's crust contains many elements which can be useful to man. Some of the common elements found are Oxygen, Iron, Aluminum, Calcium etc. Then these elements combine with one another to form useful minerals which man can use in several different ways.
ANSH CHORDIYA- 10B4