Soil types (ISO 14688)
This article describes the soil types used in the description of soil profiles within the european ISO 14688 norm. In the Netherlands, this norm is used with slight adjustments and called the NEN-EN-ISO-14688.
Soil into fractions
Within the ISO14688 soil consists of several fractions. The primary fraction (which is the most prevalent soil type within the current soil layer), and possible secondary or even tertiary fractions.
Soil types
The distinction between soil types is almost entirely decided by the grain size of the individual particles in the soil for all non-organic constituents. The organic soil type depends on the level of decomposition of the soil. The ISO 14688 contains the following soil types:
| Soil catergory | Soil type | Grain fraction |
| Very coarse soil | Large boulder | >630 mm |
| Boulder | 200 - 630 mm | |
| Cobble | 63 - 200 mm | |
| Coarse soil | Gravel | 2 - 63 mm |
| Sand | 0,063 - 2 mm | |
| Fine soil | Silt | 0,002 - 0,063 mm |
| Clay | <0,002 | |
| Organic soil | Peat | N/a |
| Gyttja | N/a | |
| Topsoil | N/a |
These individual soiltypes are described more in depth on their own respective pages; You can click a soiltype in the table to navigate to the correct page, which contains a short overview and image.
Gradations
Of Sand and Gravel, the gradations can be described as well, these come in three categories: Fine, medium and coarse. These gradations exist for silt as well, but this is too small to be determined by hand and must be done within a lab if described.
Example descriptions
The main fraction is given as a noun, while the secundary and tertiary fractions are given as adjectives or added after the main fraction in a 'With x' statement. Some examples include:
-Sandy gravel
-Coarse sandy fine gravel
-Medium sandy silt
-Fine gravelly silty coarse Sand
References
- ISO 14688