Critical sections in a Carboniferous reef knoll

Hall Hill, near Whitewell, Lancashire, northern England, is a reef knoll of Carboniferous limestone. Quarrying has exposed the beds so that the structure can be seen. The central part is a mound of unbedded calcite mudstone surrounded by bedded calcite mudstones with original dips. Coarse, well-bedded crinoidal limestone covers the knoll.