Burrowing animals like muskrats, foxes and snakes make little caves that often fall in. Earth worms and beetles honeycomb the ground with tiny tunnels. Finally men loosen the soil by plowing and building. All these things make it easier for the little water miller to wash down the good top soil.
On high mountains, nothing but bare rocks are left behind, and rain, wind and frost work all the time to wear them down. The water scours the river beds deeper, and carries as much earth as it can out into the ocean. What becomes of the good soil that is washed into the ocean? It has been ground to powder or melted to paste.
Water is very heavy. A little boy or girl cannot carry a wooden pail full of it very far. Every pint of water weighs a pound. The ocean is deep. There are hills and valleys and mountain ranges on the ocean floor, just as there are on land. Some places are as deep as our mountains are high. Tons and tons of water lie over every foot of the ocean floor, and press it smooth and hard. The under layers turn to stone. All the earthy material was sorted, so now it turns to many kinds of stone— sandstone, shale rock and slate. Far out, in the deepest part of the ocean, where sand and mud are never carried, the ocean bed is made of fish bones and shells. These are ground to white powder, by the weight of the water, and turned into chalk or limestone or white marble.
You know what a volcano is, don't you? It is a mountain with a fire in it. That fire comes from the middle of the earth. It lies far under all the land and sea. Sometimes this fire breaks through a mountain top, and it breaks through the floor of the ocean, too. When it does this sandstone is melted, and when it hardens again it becomes granite or lava rock.
There are quarries of all these stones and marbles on the land. If they were made in the bottom of the sea how did they get up on the land? They were pushed up by the fire. The fire melted and cracked and pushed, until the rocky floor of the ocean came up through the water to form rocky islands. A long string of these islands slowly became a mountain chain. In pushing up, the rock
