Ed Golson Outdoor Education

soil profile

To determine the composition of the layers of soil in the Earth, scientists study a soil profile.  This is a cross section in which the layers of the soil and the bedrock beneath the soil can be seen.  As you go deeper into the Earth, things start to change. There are layers of soil in the Earth that have different components.  The first layer on the surface of the Earth is commonly known as top soil.  This is the layer where you find most of your dead and decaying matter, like leaves and twigs and also small rock materials.  Almost all the living things that live in soil inhabit this layer. This layer is also the darkest of them all because of the types of materials present. The decaying matter found in the top soil not only covers the ground to resist erosion, but also retains water.  Another thing this decaying material does is to provide rich nutrients for the soil called humus.  These nutrients will seep down into the ground to reach the other layers.

The next layer is below the first layer.  There are no decaying materials in this layer.   This layer is called subsoil.  Although there is no decaying material, this layer does receive minerals, clay and humus from the top layer (top soil) through the process called leaching.  

The third layer is the furthest down and is called bedrock.  The components of this type of soil are mostly rocks, large and small.  This layer is the largest, and is made up of solid, unweathered rock.  

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