276 Mr. Robberds on the former Level of the German Ocean, 



Harwich, and others in that of Cromer, therefore the shells in the 

 interior valleys of Norfolk, between those two positions, must 

 necessarily belong to them, and demonstrate the existence of 

 a connected layer, concealed by beds of sand and gravel, 

 through the whole intermediate space. Mr. Taylor has over- 

 looked the influence of this habit; he has made no allowance 

 for the disposition which it produces to generalize inferences, 

 and to measure the effects of the most opposite properties in 

 nature, by one pre-conceived system and uniform scale ; he 

 has surrendered his judgement to authority — has endeavoured 

 to reconcile with the promulgated opinions of others, all that 

 has come under his own observation ; and has thus permitted 

 himself to appeal to a few fossils, taken from a single well, as 

 ^^ absolute pi-oofoi a. continuous shelly bed," although the ac- 

 tual series of the strata, laid open to day-light for the space of 

 several hundred yards within a short distance of that very 

 spot, exhibit not the faintest trace of any " continuous bed" of 

 the kind. The authority on which Mr. Taylor seems prin- 

 cipally to rely, is that of Mr. W. Smith, who has stated, that 

 «' through Norfolk the Crag shells lie near to, or are in con- 

 tact with, the top of the chalk." But whence are the facts 

 taken, on which this statement rests ? — From the vale of 

 Aylsham and the Flegg hundreds, which are portions of the 

 ancient JEstuary itself. Proofs of the general diffusion of ma- 

 rine exuviae through the whole extent of ihe valleys, multiply 

 upon me daily ; but from the higher grounds, whence alone 

 the evidence of an universal and continuous Crag stratiim 

 could be drawn, nothing has yet been adduced, to support, in 

 a satisfactory and decisive manner, the theory that has been 

 advanced. On the contrary, wherever excavations have been 

 made, that afford opportunities of exploring the nature of the 

 masses of earth above the chalk, the non-existence of a con- 

 nected shelly deposit has been actually and clearly ascertained. 

 We have therefore no proof whatever, that the accumulations 

 of shells within these valleys belong to the same a^ra and the 

 same formation, as those which in some places are found so 

 deeply buried beneath thick banks of sand and gravel. They 

 mav be — and many circumstances indicate that they certainly 

 are — monuments of distinct natural operations, proceeding 

 from separate causes, and occurring at various dates. 



An attentive consideration of geological facts has led me to 

 the conclusion, which, as I have since found, was also adopted 

 by the unfortunate Lavoisier, — viz. that the series of stratified 

 rocks and alluvial soils, which compose the surface of our 

 globe, have been produced by alternate elevations and de- 

 pressions 



