When structureless soils are ruptured, soil fragments, single grains, or both result. Structureless soil material may be either single grain or massive. Soil material of single grains lacks structure. In addition, it is loose. On rupture, more than 50 percent of the mass consists of discrete mineral particles.
Some soils have simple structure , each unit being an entity without component smaller units.
Others have compound structure , in which large units are composed of smaller units separated by persistent planes of weakness. Field terminology for soil structure consists of separate sets of terms designating each of the three properties, which by combination form the names for structure. Supplemental statements about the variations in shape of individual peds are needed in detailed descriptions of some soils. The units are flat and platelike. They are generally oriented horizontally.