The outside of the earth

We live on the surface of the earth. The surface, or crust of the earth, is made of rock. In some places, it is covered with soil. In many places, it is covered with water. All around it is air.

Some of us live on huge pieces of land called continents. A continent is like a great platform of rock that sticks up a little higer than the rest of the rocky crust.

Some of us live on smaller pieces of land called islands. An island is the top of an underwater mountain or part of a continent that has become separated from the rest of the continent.

The continents and islands where we live are surrounded by water. Water covers nearly three-fourths of the crust of the earth. Most of this water lies in enormous pits that are like great bowls in the rocky crust. These huge "bowls" of water are the oceans. Water also lies in smaller pits in the continents and islands. These inland pits of water are lakes and ponds. Water also flows in rivers and streams, from the high parts of the land down to the lakes and seas.

All around the surface of the earth is a layer of air. This layer of air is hundreds of miles (kilometers) high. The air is thickest next to the land and water. It gets thinner the higher it goes. Where the air comes to an end, outer space begins.

So that's our earth - a big, spinning, moving ball of rock and hot metal, with a thin coating of soil, water, and air on the outside.