The ultimate natural resource. Soil supports vegetation including most of the food that we eat. It houses many creatures from moles to microorganisms. It breaksdown and recycles the remains of plants and animals into mineral and organic matter. It filters water and is also used a building material for human-made structures.
The formation of soil is dependant upon parent material, climate, vegetation, topography, and time. Parent material is either rock, sediments, or organic material that morphs into soil over long periods of time. Climate along with parent material determines what types and where soils develop, which then determines what type of vegetation will grow. Topography also affects the vegetation type and climate. And time. It takes 500 years to make one inch of topsoil.*

*Source: a poster from the USGS hanging in the hallway at my college...