ABSTRACT: Caliche is a general term that describes a secondary carbonate accumulation in unconsolidated sediments, sedimentary rocks and soils under semi-arid and arid climate conditions. Caliches are composed dominantly of small calcite crystals in micrite (< 4 m) and microsparite (5-15 m) size. Small amount of diagenetic minerals such as sepiolite, palygorskite, magnesium calcite and dolomite etc. are associated with calcium carbonate (low Mg-calcite) occurrences. Caliche appears in a variety of forms such as chalky powdery, nodular, tubular, laminated crust, hardpan (indurated crust). In caliche, macroscopic rhizolithic structures and microscopic alfa and beta fabric constituents are common. Two main hypotheses which explain the origin of caliche. These are; (a) downward movement of dissolved CaCO3 (per descensum; pedogenetic); and (b) capillary rise from groundwater (per ascensum; groundwater) models. During calicheformation, calcium is providedfrom varied sources.