Showing posts with label the structure of the earth. Show all posts
Showing posts with label the structure of the earth. Show all posts

Thursday, June 6, 2013

The Structure of the Earth

In order to understand the geography of the external landforms of the earth, it is essential that we have some idea of what lies within the earth's crust. It is not possible to know exactly how the earth was formed about 4500 million years ago, but from the evidence of volcanic eruptions, earthquake waves, deep-mine operations and crutal borings the following facts are quite