According to the Unified Soil Classification System (USCS), silts and clays are classified by plotting the values of their plasticity index and liquid limit on a plasticity chart. The A-Line on the chart separates clays (given the USCS symbol "C") from silts (given the symbol "M"). LL=50% separates high plasticity soils (given the modifier symbol "H") from low plasticity soils (given the modifier symbol "L"). A soil that plots above the A-line and has LL>50% would, for example, be classified as "CH". Other possible classifications of silts and clays are "ML", "CL" and "MH". If the Atterberg limits plot in the"hatched" region on the graph near the origin, the soils are given the dual classification 'CL-ML'.