Which horizon is typically described as the horizon of weathered rock and is considered the layer of parent material?

Which horizon is typically described as the horizon of weathered rock and is considered the layer of parent material?

• A. Horizon A
• B. Horizon B
• C. Horizon C
• D. Horizon D

Answer: (C)

In soil profiles, the layer that is made up of weathered rock and serves as the source material for the upper horizons is the C horizon. It forms from the partial breakdown of the underlying bedrock and sits beneath the A and B horizons, acting as the parent material for the soil above. This horizon contains partly decomposed rock and has less organic matter and biological activity than the surface horizons, which is why it’s described as the weathered rock layer that feeds the rest of the profile. The topsoil layer is rich in organic matter and life, the subsoil is where minerals and clays accumulate, and the D horizon is not the standard weathered-rock layer in most soil classifications. So, the weathered-rock, parent-material horizon is the C horizon.

In soil profiles, the layer that is made up of weathered rock and serves as the source material for the upper horizons is the C horizon. It forms from the partial breakdown of the underlying bedrock and sits beneath the A and B horizons, acting as the parent material for the soil above. This horizon contains partly decomposed rock and has less organic matter and biological activity than the surface horizons, which is why it’s described as the weathered rock layer that feeds the rest of the profile. The topsoil layer is rich in organic matter and life, the subsoil is where minerals and clays accumulate, and the D horizon is not the standard weathered-rock layer in most soil classifications. So, the weathered-rock, parent-material horizon is the C horizon.