intraclast

thumb|Intraclasts (marked "In") in the Carmel Formation (Middle [[Jurassic) near Gunlock, Utah.]]

In geology, intraclasts are irregularly-shaped grains that form by syndepositional erosion (i.e. erosion simultaneous with deposition) of partially-lithified sediment. Gravel grade material is generally composed of whole disarticulated or broken skeletal fragments together with sand grade material of whole, disaggregated and broken skeletal debris. Such sediments can contain fragments of early cemented limestones of local origin which are known as intraclasts.