Surface and Interior of Earth

Earth, the largest and densest rocky planet, was created about 4.5 billion years ago. The earth's interior is composed mostly of iron and oxygen combined with various elements into different mineral forms. It is divided into four layers which is typical of rocky planets. The surface is unique from the other planets because it is the only one which has liquid water in such large quantities. Mountains, earthquakes, rivers, volcanoes, and deserts are all examples of surface features on the earth.