soils
Formation of Soils. According to the manner of formation, soils may be classified as follows:<br>
1) Sedimentary:
a) Residual deposits, (gravels and clays);<br>
b) cumulose deposits (peat, swamp soil, muck).<br>
2) Transported:
a) colluvial (cliff fragments and material of avalanches);
b) alluvial (marsh deposits, clays);
c) aeolian (wind blown material, sand dunes);
d) glacial deposits (morainal material).
According to the texture soils may be classified as sand, sandy loam, and clay. Loam is a mixture of sand, clay and some amount of organic matter. The term sand is used for the size of grains and not to mineral composition. Most sands consist of the harder mineral. Sand is more elastic than plastic and has no cohesion. It changes volume elastically under compression. Gravel is a mixture of sand and of larger pebbles. Clay usually contains alumina silica and water; it widely varies in colour.
