in the soil, approximately parallel to the soil surface, with properties different from layers above and/or below it. If at least one of these properties is the result of soil-forming processes, the layer is called a soil horizon. In the following, the term layer is used to indicate the possibility that soil-forming processes did not occur.

The following layers are distinguished (see Chapter 3.3 of the WRB Manual):
* Organic layers consist of organic material: Have >= 20% organic carbon,