What does the C horizon represent in soil formation?

The C horizon is a crucial component in the soil profile, representing the layer of incompletely weathered parent material. This layer is typically composed of partially disintegrated rock and weathered fragments that have yet to undergo significant soil formation processes. Unlike the layers above it, the C horizon has not experienced extensive physical or chemical changes, which means it retains many characteristics of the original parent material from which the soil is derived.

As weathering progresses downward through the soil profile, the materials in the C horizon can serve as a source for the development of the upper horizons, particularly as they undergo further weathering and mixing with organic material from the A and B horizons above. Understanding the C horizon is essential in soil science, as it influences the physical properties of the soil and informs practices related to soil management, cultivation, and engineering applications.

The other layers such as the organic layer and composite layer of minerals are distinct components that are situated above the C horizon, while the layer of leached materials relates to the effects of water movement and soil chemistry, which are not characteristic of the C horizon itself.