Fourth Grade
Worksheets
What's in the Horizon?
There are many layers of soil. Each layer is called a horizon. Each horizon is important. The surface layer of soil is known as the O horizon. This layer is about one inch thick and full of organic material. It is made up of dead things like bugs and leaves. As these materials decompose, they break down and help to make the soil healthy. The second layer is the A horizon, or topsoil. It is full of things that are alive. Roots, bacteria, and fungi live in this layer. Worms and other creatures do as well. The third layer of soil is the B horizon. .....
