- the soil profile is a cross-sectional soil layers from the surface to the soil in the bedrock
- the most common layers are the o-horizon, a-horizon, b-horizon, and c- horizon
- O-horizon is made of completely un-decomposed plant residue
- A-horizon is the top soil, contains decomposing organic material known as hummus
- Ther are lots of alive stuff in the A-horizon soil
- B-horizon is he sub-soil plant roots are in this area
- Less inorgnic and less hummus in B-horizon
- C-horizon is the bedrock