A soil horizon is a layer parallel to the soil surface, whose physical, chemical and biological characteristics differ from the layers above and beneath. Horizons are defined in many cases by obvious physical features, mainly colour and texture. These layers or horizons may be described both in absolute terms, particle size, distribution and texture, and in terms relative to the surrounding material, i.e. ‘coarser’ or ‘sandier’ than the layers above and below.
Each soil layer may be slightly or very much different from the layer above it or the one below it. Each layer also tells a story about the composition, age, texture and other characteristics of that layer. The layers are divided into topsoil layer, sub-soil layer and the bedrock layers. There are four or five soil layers or horizons depending on where the soil is formed.
- The O-horizon is organic material on the ground surface
- The A-horizon or topsoil contain humus or organic matter
- The B-horizon or subsoil contains minerals leached from the topsoil and little organic matter
- The C-horizon or weathered rock and lastly,
- The R horizon or bedrock (subsoil, regolith and bedrock).
At the listed coordinates examine the nearby nearby side of the mine shaft. Please answer the following questions and supply the answers to the cache owner.
-What are the horizons you can see? How many layers?
-What is the layer under the weathered rock? Where is the bed rock?