Smectic - Biasiallitic soil material in which smectite is the dominant mineral in the clay fraction. Typically smectite content is more than 50 percent of the clay fraction.

Biorthic - Typical bisiallitic soil material that consists of clay fractions containing appreciable amounts of vermiculite, mica and/or chlorite or identifiable amounts of smectite (usually > 10%). Various amounts of interstratified mica-vermiculite-chlorite, partially hydroxyinterlayered vermiculite or smectite, and interstratified mica-smectite have been identified in the Southern Region. Cation exchange capacities are generally greater than 30 meq/100g of clay. Typically, coarse fractions contain greater than 10% weatherable minerals.