Question

Below the C-horizon the layer is ____________ which is hard and difficult to dig with a spade.

Answer 1

Layer parallel to the soil surface whose physical, chemical and biological properties are different from the layers above and below is called soil horizon. In many cases, horizons are defined by obvious physical characteristics, primarily color and texture.

Complete answer:
The C horizon is a mineral horizon that does not include the hard and strongly cemented bedrock below it. The horizon is little influenced by pedogenic processes and, by definition, does not have the properties of the O, A, E or B horizons.

The C horizon also includes layers of silica and calcareous like mussels, corals, and diatomaceous earth. Many soils contain a C horizon above the bedrock, called the R layer in soil taxonomy, with the exception of some heavily weathered soils. In many soils, the bedrock is below 200 cm deep. However, soils formed in loose geological deposits such as alluvium, colluvium, loess, or volcanic deposits can have bedrock at great depths. In addition, soils formed on loess and thin tephra deposits accumulated in an incremental way generally do not have a C horizon, since all parts of such soils show signs of pedogenic alteration.

Bedrock is the hard, solid rock found beneath surface materials, such as dirt and gravel. Bedrock is also found under sand and other sediments at the bottom of the ocean. The bedrock is consolidated rock, that means, it is tight and strongly united. The material that covers it is usually loose rock formed by loose particles. The bedrock can extend hundreds of meters below the earth's surface, all the way to the bottom of the earth's crust. The upper limit of the bedrock is called the rock head.

Thus, the correct answer is Bedrock.

Note: Above the rockhead, the bedrock can be covered with saprolite. Saprolite is a bedrock that has been exposed to severe weathering or wear. Saprolite has gone through the process of chemical weathering. This means that saprolite is not only a less consolidated bedrock, it also has a different chemical composition.