Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/632

 of boulders from a great distance, and that, during the formation of the lower Coralline Crag, movements of subsidence prevailed, succeeded in the upper division by an elevation of the sea-bed, which brought the Coralline Crag partly above the sea-level, where it became exposed to the action of the tides, currents, and breakers of the Red-Crag sea. In consequence of this action, a very large portion of the Coralline Crag has been destroyed, and its debris incorporated in the mass of the Red Crag ; and the beds of phosphatic nodules (or the Coprolite-beds) of the Red Crag are probably derived in whole or in greater part from the Coralline Crag. Floes laden with large unworn flints from the neighbouring chalk coast were stranded on the Sutton Coralline-Crag islets, whilst shore-ice floating off from the same islets strewed the sea-bed around them with large blocks and boulders of the Coralline Crag.

The Norwich Crag, which occupies the contiguous area, and lies on the same level, seems to have been divided from the more open sea of the Red Crag by a barrier of Coralline Crag, behind which were sandy bays, into which flowed a river or rivers bringing down land and freshwater shells, and probably mammalian remains from land to the north-west and west. There is evidence of these streams coming from that direction in the circumstance that in the Crag at Norwich, Lias Ammonites, Mountain-Limestone corals, besides the many fossils from the Chalk, are found. I have found also, at the base of the Crag at Weybourne, a fragment of fossiliferous Kimmeridge Clay, and in the Norwich Crag an encrinital column similar to some I have seen in the Red Crag of Suffolk, in which latter also occur Belem- nites, Ammonites, Ostrece, and Terebratulce from various Secondary rocks, together with fragments of chert from the Lower Greensand, while the occurrence of the fragments of red granite points to trans- port from still more distant localities*.

After a time a general subsidence of the whole area took place, followed by the deposit of the Chillesford sands over the irregular surface of the Coralline Crag, Red Crag, and Norwich Crag, and at the same time colder currents from the north introduced new and more Arctic species of Mollusca. Still notwithstanding the greater depth of water and the greater cold, there is an absence of all foreign boulders, with the exception, if they may be so termed, of large blocks of subangular chalk-flints.

The sea-bed was then raised and a land surface formed in eastern Norfolk, and over some adjacent part of the German Ocean. On this freshwater deposits were formed, and a forest of Scotch firs, Norway spruce and other trees of a temperate character grew. The forest was frequented by herds of deer, whose shed antlers are found in abundance (Woodward), as well as by troops of Elephas antiquus.

Another subsidence then took place submerging the whole forest,

modifying the Crag-fauna, see Godwin- Austen " On the Kainozoic Formations of Belgium ' (Quart. Journ. Geol. Soc. vol. xxii. p. 228).
 * For considerations on the subject of the old Crag-area, and on the causes