After a rock breaks down, materials that are left combine with organic materials to form

Here is the complete sentence: After a rock break down, materials that are left combine with organic materials to form SOIL.

The process by which rocks are broken down is called weathering. There are different type of weathering, but the resultant effect of all of them is to break down rocks into smaller particles. The broken down particles usually combine with mineral content, moisture, gases and humus in order to form a complete soil.