SEPM Strata


coquina
igneous rocks metamorphic rocks minerals sedimentary rocks	formation & Environments coquina is a limestone consisting almost completely of mechanically transported fossil debris with little or no matrix, loosely cemented together so that the rock looks very porous. Such rocks form in zones of high energy where finer material is winnowed away. Typically the shells are clams and snails. Description Badly broken, current washed, relatively well sorted, poorly cemented bivalve shell debris. Composition Shell debris, sometimes whole; typically broken and wave washed. Tectonic Association None specific, although coquinas form in conditions favorable to limestone formation. Detail Description In this closeup we can see in the two larger pieces the evidence of clam shells. Everything else is badly broken and abraded, although well sorted to size. Composition Shell debris, sometimes whole; typically broken and wave washed.