Cliffs at Hunstanton, Norfolk showing three distinct layers of rock; nearest the beach is Carstone (40- 58ft, 12-17m thick), thin layer of Red Rock (4ft 1. 2m) topped by Cenomanian chalk (18ft, 5. 5m). Carstone (ginger brown) is a coarse & gritty sandstone from the Lower Cretaceous. It contains large quantities of iron & the minerals kyanite, staurolite, tourmaline, rutile & zircon. The stratum of Red Rock (young lower Cretaceous) is a continuation of the Gault Clay & consists of a pink ferruginous (iron) limestone layer with peebles scattered in it. The Cenomanian chalk layer (Upper Cretaceous) contains fine calcite crystals, making this chalk harder than average.