Olistostrome

An olistostrome is a sedimentary deposit composed of a chaotic mass of heterogeneous material, such as blocks and mud, known as olistoliths, that accumulates as a semifluid body by submarine gravity sliding or slumping of the unconsolidated sediments. It is a mappable stratigraphic unit which lacks true bedding, but is intercalated amongst normal bedding sequences, as in the Cenozoic basin of central Sicily. The term olistostrome is derived from the Greek olistomai (to slide) and stroma (accumulation).

Olistostromes are mélanges formed by gravitational sliding under water and accumulation of flow as a semi fluid body with no bedding.