Ground retraction is due to
a reduction in water levels.
Clay is plastic when high on water content but becomes hard and non plastic upon drying.
Depending on the soil's composition, clay can appear in various colors.
Clay is a fine grained natural rock or soil material that combines clay minerals with traces of metal oxides and organic matter.
It is an important constituent of soils and has been useful to humans since ancient times
in agriculture, building and manufacturing.