Soil profiles

When parent rock weathers, layers are formed. Together these layers form what is called a soil profile.

Sometimes you can see these layers in a roadside bank, or you can dig a hole deep enough to expose the different layers beneath the surface.

Here is a standard soil profile.

Different soils develop in different areas depending on:

• the type of parent rock
• the surrounding environment
• climate
• intervention by humans.

Some soil profiles contain different layers that are unrelated to the parent rock underneath them. For example:

• layers of silt or sand from rivers flooding at some stage
• ash from volcanic eruption
• windblown soil particles (loess).

There will be very little or no topsoil if it has been removed by humans or a landslip. Topsoil is often removed from a new housing development and then it is sold. When the new home owners come to carry out landscaping they may have to buy in topsoil from another location to replace what has been removed.

What's next?

Go to: 3 Soil texture.