What is solid rock under the soil called?
The hard, solid rock beneath the soil surface is called the bedrock. The bedrock may be made up of any of the several types of rocks including granite, limestone, sandstone, etc. In engineering geology, the part of bedrock that underlies the loose soil is called rockhead. In civil engineering, identifying the properties of rockhead by drilling, boring, excavation, etc. is an important activity and helps in site selection, foundation design and material selection, among other things. In some areas, the top strata may be hundreds of meters thick, thus the bedrock is very deeply buried in the surface. Bedrock characteristics and depth may also be used to determine the level of ground water and the aquifer properties and whether ground water can be harvested.