Here's a breakdown of the typical soil horizons:

* O Horizon (Organic Layer): This is the top layer, composed of decomposed plant and animal matter (humus).

* A Horizon (Topsoil): This layer is a mix of minerals and organic matter, often rich in nutrients and ideal for plant growth.

* B Horizon (Subsoil): This layer is richer in minerals and less organic matter than the A horizon. It often has a different color and texture.

* C Horizon (Parent Material): This is the layer from which the soil is formed. It consists of weathered bedrock or unconsolidated material.

* R Horizon (Bedrock): This is the solid, unweathered rock that lies beneath the soil.

So, the C horizon is essentially the partially weathered material that the soil above it was formed from. It's often a mix of rocks, gravel, and minerals.