Crag.
A layer of which, between the watch-house and coal gaps at Bacton, has been termed by Mr. Lyell hard ferruginous crag. It consists of several thin plates, containing compressed wood, fragmentary and whole shells, intermixed with clay, gravel, and white sand. This bed forms a dip towards the north-west, having a support of red sand on the one side, and green sand on the other. A section of the crag is more largely developed at Cromer, Runton, and Weybourne. Between Bacton coal gap and Mundsley, vertical layers of crag occur, composed of thickly cemented fragments of shells.
Immediately beneath the crag occur those formations which are generally termed Fresh Water, consisting of lignite and lacustrine deposits.
Lacustrine.
At several spots between Hasborough and Mundsley, these deposits may be examined. They contain many species of shells, with fish and bones of mammalia.
The first of these occurs at a place called Ostend, between Hasborough and Bacton, about half a mile from the latter place. It is composed of bluish mud, with occasional patches of brown clay, and extends several yards along the beach. This formation was discovered by Mr. Green, in August, 1841.
About two hundred yards from the forest peat at Bacton, the second lacustrine bed occurs. It is confined to occasional patches about the middle of the cliff, near the watch-house gap. The shells are deposited in thin layers of sand and blue clay, containing much wood, which appears as if bored by some insect.
The third lacustrine formation is at the village of Mundsley, and is distinguished from the other cliffs by its dark muddy appearance. Its height is about twenty feet, and it extends one hundred yards along the beach.
Mr. Lyell, referring to this bed, says, “It consists of brown, black, and grey sand, and loam mixed with vegetable matter, sometimes almost passing into a kind of peaty earth, containing much pyrites.”