(i) Genetic - A natural subsurface soil layer with low or very low hydraulic conductivity and differing in certain physical and chemical properties from the soil immediately above or below the pan. (ii) Pressure or Induced - A subsurface horizon or soil layer having a higher bulk density and a lower total porosity than the soil directly above or below it, as a result of pressure that has been applied by normal tillage operations or by other artificial means. Frequently referred to as plowpan, plowsole, or traffic pan.