Introduction 

Man lives on the earth. It is the world of every one of us. It is the home for man as well as for other animals and trees. The earth provides food and other necessities for all of us. All animals and vegetation living on earth are different from each other. These differences occurred due to the changes in the environment of various parts of the earth. The earth affected man, other animals and vegetation equally. Therefore, it is important for everyone of us to learn something about the earth on which we live. In this lesson you will learn about the formation of the earth and the origin of species on it.