Surface-water-gley developed in glacial "till", Northern Ireland.

Loess field in Germany (loess is wind-blown dust that is mostly silt)

A, B, and C represent the soil profile; A is the topsoil; B is a loose soil; C is weathered rock; the bottom-most layer is the bedrock.

Soil is loose stuff which lies on top of the land. It has many things in it, like tiny bits of rock, minerals, water and air. Soil also has living things and dead things, called organic matter.

Soil is important for life on Earth because soil holds water and nutrients. It is a very good place for plants to grow. Soil holds the roots, and lets plants stand above the ground to collect the light they need to live. Almost as important are the fungi. There are fungi which grow into plant roots, a symbiosis known as mycorrhiza. This helps trees grow. There are many other fungi that live by breaking down dead organic material: the remains of other living things. The broken down material is a main source of plant nutrients. The soil also has many microorganisms living in it. Many of them eat the organic material in the soil. They use oxygen and release carbon dioxide. They also release mineral nutrients into the soil.