Here's a breakdown:
* R horizon: This is the deepest layer of the soil profile, consisting of unweathered bedrock. This is where the initial process of weathering begins.
* Weathering: Physical, chemical, and biological processes break down the bedrock into smaller particles, creating the foundation for soil development.
While the R horizon is where weathering starts, the O, A, E, B, and C horizons above it are also influenced by the breakdown of bedrock. These horizons are formed from the weathered material transported upwards, mixed with organic matter and other components.
Think of it as a continuous process:
1. R horizon: Weathering breaks down bedrock.
2. C horizon: Weathered material is transported upwards.
3. B, E, and A horizons: Further weathering, mixing with organic matter, and other processes lead to the formation of distinct soil layers.
4. O horizon: The top layer of soil, consisting of decomposed organic matter.
Therefore, while the R horizon is the primary site of rock weathering, the entire soil profile is a result of this ongoing process.
