How Soil is Formed Rock is not solid. It contains many tiny cracks and pores.
Soil starts to form when there is a cycle of freezing and thawing of the moisture around the rock.
In the fall when it rains, the moisture seeps into the cracks and pores. Freezing cold weather causes the ice that forms to expand, forcing the rock apart. Over many years, this cycle and other natural environmental forces break down the rock into smaller and smaller pieces. These chunks of rock are called the parent materials. Gradually this parent material is broken down into particles of minerals.