Classification of accumulations of clay illuvial


At a microscopic level, illuvial clay accumulations are classified according to their particular characteristics.


Morphological classification

Coatings.These are pedofeatures that coat the surfaces of voids, grains or aggregates. These films are called clay skins and in Brewer's terminology (1964) cutans and argillans.


Quasi-coatings. These are related to surfaces of voids but not immediately adjoining them.

Infillings. These are formed of clay material. Two types can be established according to whether they completely fill the pore or not (dense or loose).

Fragments. They are remains of illuvial clay accumulations, deformed by pedological processes.

They are fairly deformed fragments which in some areas show the strong characteristic orientation of illuvial clay, their edges are often clear and they are found in the soil mass, without any apparent association with the pores. According to Brewer (1964), they correspond to papules.


Classification according to particle size

Depending on whether the accumulations are made up of pure clay or this is accompanied by silt-sized particles, two main types can be distinguished:

Limpid clay

Impure clay


Classification according to internal fabric

Non-laminated. Homogenous masses are a common type of illuvial clay accumulations.


Microlaminated. Frequently, illuvial clay accumulations show a fine lamination, alternating thin (<30 microns) laminae of limpid clay with different colourings.

Compound layered. Alternating layers of two or even more components.


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