The Delft Sand, Clay & Rock Cutting Model, 2019a

The Delft Sand, Clay & Rock Cutting Model.
widely varying particle sizes. Gravity on its own may also carry particles down from the top of a mountain to make
a pile of soil and boulders at the base; soil deposits transported by gravity are called colluvium.
The mechanism of transport also has a major effect on the particle shape. For example, low velocity grinding in a
river bed will produce rounded particles. Freshly fractured colluvium particles often have a very angular shape.
2.2.3. Soil Classification.
Soil classification deals with the systematic categorization of soils based on distinguishing characteristics as well
as criteria that dictate choices in use.
Figure 2-3: Soil naming according to USDA.
Soil texture is a qualitative classification tool used in both the field and laboratory to determine classes for
agricultural soils based on their physical texture. The classes are distinguished in the field by the 'textural feel'
which can be further clarified by separating the relative proportions of sand, silt and clay using grading sieves:
The Particle Size Distribution (PSD). The class is then used to determine crop suitability and to approximate the
soils responses to environmental and management conditions such as drought or calcium (lime) requirements. A
qualitative rather than a quantitative tool it is a fast, simple and effective means to assess the soils physical
characteristics. Although the U.S.D.A. system uses 12 classes whilst the U.K.-ADAS uses just 11 the systems are
mutually compatible as shown in the combined soil textural triangle below.
Hand analysis, whilst an arbitrary technique, is an extremely simple and effective means to rapidly assess and
classify a soils physical condition. Correctly executed the procedure allows for rapid and frequent assessment of
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