28i Mr. R. C. Taylor on the Geology of East Norfolk. 



assumes the appearance of a gray sandstone ; in others the 

 shells are detected in an extremely hard clay-stone ; but in- 

 stances occasionally occur where organic remains are alto- 

 gether wanting. 



In remarking upon the absence, at Bramerton, of a parti- 

 cular shell, which is met with among the crag fossils of Har- 

 wich, Mr. Robberds considers that this circumstance alone is 

 fatal to the opinion entertained by me, of the continuity of the 

 formation. But it must be remarked, that it is characteristic 

 of the shells and other organic bodies deposited with the crag ; 

 that they are by no means diffused in equal numbers and pro- 

 portions throughout, as in some older strata ; but occur at in- 

 tervals, in groups and genera. Thus at Cromer the predo- 

 minant and remarkable shells aveMactrcs; at Runton, Cardico; 

 nearer Cley, Murex striatiiS; at Bawdesey cliff, Murex re- 

 versiis, and Pectunculus ; at the Beacon, Venus cequalis; at Felix 

 Stow, Pectunculus and Valuta Lamherti; south of Languard 

 Cottage, Murex contrariiis, Carditr, and Mj/a lata : at Bramer- 

 ton and near Norwich are Murex striatus, Tellince and Da- 

 lani. The absence, therefore, of one or of many species from 

 any of these localities, cannot weaken the remaining concur- 

 rent evidences that identify this formation, nor can it lead to 

 the confounding it with any other. 



The shells of Bramerton, and other parts of the Norwich 

 valley, consequently, belong to the crag formation, and are 

 not an assemblage simply of the recent species which abound 

 in our seas, although they are mixed with many that closely 

 resemble the existing varieties. 



Mr. William Smith, than whom a belter practical authority 

 on this question cannot be quoted, states that " through Nor- 

 folk the crag shells lie near to, or are in contact with the top 

 of the chalk ; and under a loamy soil, on or near some of the 

 best land in Flegg and the Vale of Aylsham." 



On the contrary, Mr. Robberds's experience goes to prove, 

 — and without it his views of the flowing of the ocean tides 

 through the Norwich valley at 40 feet elevation, cannot be 

 sustained, — that the shells so far from being stratified, form 

 only a beach or belt, in no case penetrating into the sides of 

 the hills. That this may be partially and occasionally the 

 case, it is by no means here intended to doubt, particularly 

 after the positive investigation to which this point has been 

 subjected. There are difficulties in discovering a vein of coal 

 or a bed of iron-mine, even in the exposed face of a rock or 

 mountain: how many impediments prevent the tracing any 

 thin or soft stratum, in a liighly cultivated country, thickly 

 ovcispread with diluvial and alluvial substances ! Norwich is 



nearlv 



