91Ó°ÊÓ

The outer loose layer on the earth’s surface is known as soil. Soil is very much important for land plants. Soil formation is a slow process and it takes many years to form from rocks, organic substances, and minerals.

Different layers of soil constitutively make the soil profile. Bedrocks are the solid rock beneath surface materials such as gravel and soil. The physical characteristics are such as, the bedrocks are hard. Rockhead is the surface of bedrock that is present beneath the soil. Weathering of bedrock forms mineral soils.

Sand forms by continuous weathering of rocks for thousands of years. These particles have a diameter ranging from 0.1 to 2 mm.

Clay soil is even smaller than sand and silt. The diameter is less than 0.002 mm.

Loam soils are a mixture of various soil types and have no dominant type.

The correct option is (b)

Bedrocks are the solid rocks that lie beneath the soil.