Soil of these properties determine the aeration of the soil and the ability of water to infiltrate and to be held within the soil. The mineral components of soil are sand, silt and clay, and their relative proportions determine a soil's texture. Properties that are influenced by soil texture include porosity, permeability, infiltration, shrink-swell rate, water-holding capacity, and susceptibility to erosion. In the illustrated USDA textural classification triangle, the only soil in which neither sand, silt nor clay predominates is called loam. While even pure sand, silt or clay may be considered a soil, from the perspective of conventional agriculture a
Parramatta Sand Body Conservation Area and Military Barracks Site and slightly mottled with depth. The upper parts of the soil profile are usually heavily mixed, especially by cicada larvae. In places the sand is cut by deposits of mottled or gleyed clay that were probably deposited in swamps or waterholes on the terrace surface. The reasonably defined levee, 50 to 100 centimetres high, along the terrace edge between Charles and Alfred Streets, comprises cleaner and very slightly coarser sand than the sand found around the margins of the levee. The profile of the sand suggests that the main body of sand is of late Pleistocene age and recent thermoluminesence