# Hardpan (Caliche)

“Hardpan” is a highly dense and solid layer of soil near the ground surface, which is usually comprised of clay or silty-clay soils. Hardpan forms by cementation over time, during the process of precipitation of insoluble substances such as calcium carbonates, silica, iron oxides, and other organic matter. “Hardpan” is a term mostly used by farmers and agricultural technicians. However, in the field of geology, Hardpan is generally referred to as “Caliche.” Other names for the substance include “Calcrete,” “Calcic Rock,” and/or “Duricrust.”