What characterizes the middle layer of a soil profile?

The middle layer of a soil profile, often referred to as the B horizon or subsoil, is characterized by being a weathered layer that has undergone various degrees of leaching and accumulation of materials like clay, minerals, and other elements derived from the layers above it. This layer typically shows evidence of weathering but contains less organic matter compared to the upper layer, where organic material accumulates due to the decay of plant and animal matter.

In contrast to organic-rich topsoil, the middle layer lacks significant amounts of decomposed organic matter, which is typically more prevalent in the upper layers. The processes occurring in this layer involve the movement and deposition of minerals and clay particles, leading to a more compacted and sometimes higher clay content, differentiating it from the surface horizon.

The choices relating to high organic matter content, unweathered bedrock, and a clay and gravel mixture do not accurately describe the characteristics of the middle layer. High organic matter content is associated with the topsoil layer, unweathered bedrock pertains to the deepest geological layer, and a mixture of clay and gravel does not specifically represent the weathering characteristics found in the subsoil. Instead, the correct characterization reflects the soil's transitional nature where it is influenced by the layering