276 Mr. Rose's Sketch of the Geology of West Norfolk. 



the equivalent of the upper green-sand or frestone ; and the 

 gray bed that of the chalk-marl; but I find the characteristic 

 fossils of the upper green-sand, and chalk-marl so intermingled 

 in the gray bed, that it is impossible to draw a line of de- 

 marcation between those two strata; and from this circum- 

 stance we are led to infer that at the epoch when the upper 

 green-sand and chalk-marl of Wiltshire and Devonshire were 

 depositing, and the then existing marine Testaceae were en- 

 tombed, similar phenomena were in progress in this portion of 

 the great chalk basin ; but the material supplied being more 

 cretaceous, the strata consequently exhibited a dissimilar mi- 

 neralogical character. The lowest of these beds (No. 4, of 

 the section of Hunstanton Cliff) reposes upon the thin seam 

 of dark red argillaceous matter (described page 181), which 

 separates it from the red limestone or gault equivalent. The 

 texture of this bed varies, some portions of it being very 

 loose, others exceedingly hard and compact; its substance is 

 throughout intersected by a ramose zoophyte*, the original 

 texture of which is so completely obliterated, that it appears 

 impossible to determine precisely the nature of what it is the 

 relic : the formation of the stratum is best explained by sup- 

 posing it originally a coral reef, and its interstices filled with 

 cretaceous mud; it is about eighteen inches in thickness, and 

 contains very few organic remains. Chalk resembling it in 

 hardness and fracture occurs at Heytesbury in Wiltshire. 



The next bed in the ascending series to be described, is 

 No. 3 of the same section. Its colour is gray, and its texture 

 less compact than the harder parts of the last- mentioned; on 

 being fractured it exhibits an arenaceous surface, from its 

 having a larger proportion of silex incorporated than the 

 white chalk above. It is probable that this stratum at the 

 cliff receives its hardness from the action of sea- water upon 

 it; for the chalk of the same bed met with inland can be cut 

 with a common knife, being much softer. This bed abounds 

 with organic remains, and contains the characteristic Testacea 

 of the upper green-sand, and also of the chalk-marl, viz. 

 Ostrea carinata and Turrilites tuber culatus. In this bed at 

 Hunstanton are found the Saurian remains ; and I believe 

 their charnel-house is at present confined to one block. The 

 thickness of this bed varies from two feet and a half to three 

 feet. Large flattened Ammonites occur in it, also a Nautilus; 

 and innumerable fragments of ' Inoceramus Cripsii are scattered 

 through it. 



A stratum containing similar fossil remains is seen at Sand- 



* A nearly corresponding bed, composed of ramose zoophytes, occurs 

 in Sussex : vide Geology of S.-E. of England, p. 384 note d. 



