Charles Brooks.: age 13, of Albany, New York, for his question:
How does water make rocks?
The heat from a blazing fire will boil water and turn it into gasey steam., A cold morning will freeze it into solid see. Our earth was once a mass of seething gases, and lower temperatures turned it solid. The ground on which we stands way down to the heavier materials in the heart of the earth, is the solid frozen form of once steaming gases.
Some of the gases either filed to cool enough to become solid or else were heated up again to liquid and gaseous state. Since gases and liquids are better able to get around than solids, they can move about and cause changes in the solid materials. Most of the changes on the solid grid have been made by flowing water.
Day after rainy day, through eons of time, its greedy tongues have been pulling at the solid rocks. It dissolves chemicals and tiny fragments of solid material and carries them away. But it can carry only just so much solid material and when it reaches the sets or some quiet lake it has to drop much of its plunder in a layer of mud.
In its youth, the solid earth was more restless. It heaved and tossed.. A low, water filled basin would rise and high, dry area would sink the land and the sea often changed places. Many a layer of mud dumped under water by the busy streams often rosy up to the land, only to sink and collect a new layer of mud under the sea,
Under the weight of new layers, the old layers were often pressed into slabs of slate and shale. These are some of the earliest beds of rock to be made on the earth's crust. And, in a sense, the slates and shales were made by running water.
Other water formed rocks can be seen in all their beauty hanging from the ceilings and rising from the floors of certain damp coves. Here, water has flowed underground and gathered itself loads of chemicals, chiefly calcium carbonate dissolved from the rocks. Water tends to evaporate faster when spread into small shallow quantities and when it evaporates it must leave most of its chemicals and solid plunder behind
As the slow drip drip of water seeps through the ceiling of the cave much of it evaporates. A bump of calcium is left behind, growing like an icicle into a slender hanging stalactite. The dripping water flows around the growing stone, spreading over a bigger area and depositing still more new stone. Some falls upon the floor below and a hump of solid stone grows upwards in a column as a stalagmite to meet and join the hanging stalactite.
Actually, water does not make stones in the sense of manufacturing solids. It dissolves stones end carries away their solid fragments to form new stones.