In a wet climate, water seeping down through the
soil leache soluble ions from both the A and B horizons.
The less soluble elements, such as aluminum, iron, and
some silicon, remain behind, accumulating in the B horizon
to form a soil type called a pedalfer (Fig. 6–17b).
The subsoil in a pedalfer is commonly rich in clay, which
is mostly aluminum and silicon, and has the reddish
color of iron oxide.