Caliche

Caliche is a broad term that applies to sediment (sand, silt, clay, and gravel) or soil that has been cemented together, often with calcite, in an arid or semiarid region. It may occur as small nodules in silt deposits or in continuous beds that stretch for miles. Often found on or near the surface, caliche is usually soft, but older deposits can be very hard and thick. The term "caliche" is also sometimes used to refer to the cementing material itself. In some places, caliche is called hardpan or calcrete. It can be used to make cement or as a base for roads.