If we take some water from a river in full flow or from a pond after a while certain particles will fall to the bottom of the glass or receptacle. These particles previously floated in the water giving it a brown muddy color.

We can imagine what this process would be like magnified many millions of times and occurring for long periods. This is how clay deposits gather.

Rocks and pebbles require quite strong force to move them along, but the fine particles of clay are so light that they float in the water and are borne along for great distances in rivers to the sea. When these clay particles finally come to rest they form what is known as argillaceous or clay rocks. These rocks are very fine grained and smooth and many become soft if soaked in water.

Clays are basically made up of silica, aluminum and water in various amounts together with other elements such as iron, calcium, chalk and mica. No other earth material has so many uses or such a wide importance. One of the purest forms of clay is kaolin which is used in making porcelain and china. Impure clays have been used for bricks, tiles and the crude types of pottery since the earliest times.