Which layer lies beneath the topsoil in a normal soil profile?

• A. Bedrock
• B. Topsoil
• C. Humus
• D. Subsoil

Answer: (D)

In a normal soil profile, horizons run from the surface downward, with organic material and minerals forming the uppermost layers. Beneath the topsoil sits the subsoil. This B horizon gathers minerals leached from above and often contains more clay and oxides of iron and aluminum, while having less organic matter than the topsoil. Its color and texture reflect those mineral accumulations, and it lies above the even more weathered parent material. Humus is the decomposed organic matter mainly in the upper horizons, and bedrock sits below the subsoil and the other lower layers.