Usually lighter in colour than the topsoil, colour change often very distinct;
Zone of accumulation where the clay partials tends to accumulate.
Zone tends to be wetter and heavier in texture, denser.
Can have a good nutrient content from minerals leaching down plus the buffering effect of the clay.
Less nitrogen as there is less oxygen for the aerobic reaction of bacteria.
Can become water-logged,
iron/clay and plough pans can form in this layer `