The Ever Changing Earth: Introduction, Erosion, Earthquakes, Questions

The compilation of these Our Changing Earth Notes makes students exam preparation simpler and organised.

The Ever Changing Earth

Earth is the only planet where living things can survive. As it is the only planet which has water. But that the earth remained the same since ancient times? No, right? The earth has been changing constantly. Let’s find out more about Our Changing Earth.

Introduction to Our Changing Earth

The Earth is the third planet in the solar system. It is also the only planet where living things can survive. About 71 percent of the earth is covered in water the rest 29 percent is land. However, only 3 percent of this water is fresh water and only. The earth’s atmosphere is made up of the exosphere, thermosphere, mesosphere, stratosphere, and troposphere. And the earth’s composition is made up of the crust, upper mantle, mantle, outer core, and inner core.

Introduction to Our Changing Earth

In earth science, erosion is the action of surface processes (such as water flow or wind) that removes soil, rock or dissolved material from one location on the Earth’s crust, and then transport it away to another location (not to be confused with weathering which involves no movement).

An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth’s lithosphere that creates seismic waves. Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to toss people around and destroy whole cities.


Question 1.
The earth’s plate responsible for causing earthquakes is _________
a. The crust of the earth
b. Mantle of the earth
c. The outer core of the earth
d. The Inner core of the earth
The earth’s plate responsible for causing earthquakes is the crust of the changing earth. Most earthquakes occur along the edge of the oceanic and continental plates. The earth’s crust (the outer layer of the planet) is made up of several pieces, called plates. The plates under the oceans are called oceanic plates and the rest are continental plates.

The plates are moved around by the motion of a deeper part of the earth (the mantle) that lies underneath the crust. These plates are always bumping into each other, pulling away from each other, or past each other. The plates usually move at about the same speed that your fingernails grow. Earthquakes usually occur where two plates are running into each other or sliding past each other. Therefore, the correct answer is option “a”.

Question 2.
The most destructive earthquake waves are ___________
a. primary waves
b. secondary waves
c. surface waves
d. all of these
The correct answer is option “c”.

During an earthquake, surface waves are the seismic waves that cause the most damage. Unlike other seismic waves that move deep inside the changing Earth, surface waves move along just under the surface of the Earth like waves in water. Surface waves are the slowest seismic waves and are the final waves to hit an area after an earthquake.

First, P-waves move through compression through the deep layers of the Earth. They result in minimal damage. The second group of waves is S-waves. They move up and down starting deeper in the Earth. Stronger S-waves do some damage when they reach the surface. Surface waves move at last. Their slow roll just under the surface provides the greatest risk for damage to man-made structures and changes to natural landforms.