CRAG OF NORFOluK. 



235 



what has generally been given. He proposes to state his opinions on 

 this subject in a subsequent work. 



Dr. Buckland has pointed out many situations west of the London 

 clay, where patches of the lower beds occur. These patches indi- 

 cate that what is called the London Basin, and the basin of the Isle 

 of Wight, were once continuous, and that iheir continuity was bro- 

 ken by the upheaving of the chalk, which, in several parts, had lifted 

 up the portions of tertiary strata that still renfiain. 



The formation called Norfolk Crag, remains to be noticed as the 

 last of the English tertiary formations. 



In the counties of Norfolk and Suffolk, there is a series of irregu- 

 lar beds of ferruginous sand and clay, mixed with marine shells, 

 which has received the name of crag. The beds are much con- 

 torted and broken, and are intermixed with London clay and chalk, 

 on which they rest ; they are covered in many parts by diluvium. 

 The crag is considered as the most recent of the tertiary beds in Eng- 

 land ; its true geological position, in relation to the tertiary strata on 

 the Continent, is not precisely ascertained. According to an account 

 of Mr. S. Woodward of Norwich, the crag is of hmited extent in 

 situ, in the county of Norfolk. If a line be drawn from Cromer, 

 on the northern coast of Norfolk, to Wayburn, about six miles west, 

 and from thence extending southerly towards Norwich (about eight- 

 een miles,) it will comprise all the regular beds of crag. Mr. Wood- 

 ward supposes that these beds were deposited in an estuary ; east- 

 ward of this tract, ligneous and mammalian remains have been found 

 in abundance, indicating that it was once dry land. (Mag. of Nat. 

 Hist. Sept. 1832.) According to Mr. R. C. Taylor, the crag forms 

 the base of the cliffs, from Cromer to Trimmingham. In a valua- 

 ble paper on the Geology of East Norfolk, by the same gentleman, 

 published in the Philosophical Magazine and Annals of Philosophy, 

 April, 1827, and the following numbers, there is an interesting ac- 

 count of the geological position of the crag near the coast, with ex- 

 planatory sections. " The crag rests in part upon the London clay, 

 and a laminated clay without fossils, and partly upon chalk, occupy- 

 ing the lowest sites ; rarely rising to eighty feet above the present 

 level of the sea, and in general not more than half that elevation. 

 The average level of its base may be considered to be about that of 

 the present ocean. In certain cases, where the chalk hills attain a 

 higher level than the crag, that deposit could be expected only to en- 

 velope or surround their sides, and not to penetrate into the chalk : 

 such eminences would then present the appearance of tongues or 

 promontories of chalk, protruding into the crag ; and this circum- 

 stance accounts for the occasionally apparent absence of that forma- 

 tion. But the crag has been subjected to abrasion by diluvial cur- 

 rents. Portions of its western edges have been swept away. Their 

 fragments, mingled with those of chalk and preceding formations, 

 piled in enormous heaps, form the cliffs of Cromer and Trimingham,^ 



