m reply to Mr. R. C. Taylor. 277 



pressions of the sea. These changes I conceive to have been 

 effected by successive transfers of the existing body of water 

 from one hemisphere to the other ; and the sokition of the 

 problem, which they exhibit, appears to be connected with 

 some of the most interesting astronomical phagnomena, dis- 

 played in the history of the heavens. I have been induced 

 thus to anticipate the course of my inquiry, and to point out 

 the nature of the general inferences which I shall hereafter 

 draw from a long chain of evidence, in order to explain my 

 view of the distinction between the Crag stratum and the 

 shelly deposits of the Norfolk valleys. The chalk which con- 

 stitutes so large and important a feature in the central basin 

 of Europe, was formed in the bosom of a tranquil ocean, whose 

 surface must have been more than 1000 feet above that of the 

 sea, now existing in this quarter of the globe. Beneath the 

 present level of those seas, we find the most decided traces of 

 submerged forest-land, at points so distant from each other 

 and over spaces so extensive, that the fact cannot possibly be 

 accounted for by any subsidence or sinking of the ground on 

 which these trees were produced. From the nature of their 

 remains it is evident, that they can have flourished only on 

 dry land; and as they grew in some of the lowest hollows of 

 the chalk, it is equally clear, that the waters, in which that 

 foi*mation was consolidated, must have been withdrawn to 

 such an extent as to leave uncovered considerable tracts, which 

 at this time are constantly overflowed by die tides. During 

 this retreat of the waters, their level appears to have been 

 subject to repeated minor fluctuations, and the lower basins 

 of the chalk were filled with beds of sand and clay, which in 

 some districts exhibit the vestiges of fresh-water tribes, alter- 

 nating with the marine exuviae of an intermediate date. These 

 beds seem scarcely to have extended into Norfolk, where the 

 general range of the chalk was probably above their level ; 

 some portions of them may however rest in the deepest bot- 

 toms of the valleys, and on the declivities of thepi-esent coast; 

 and it was perhaps on their surface that the foi'ests arose and 

 the animals lived, which a subsequent catastrophe over- 

 whelmed*. At the period to which I am referring, there was 

 no variety of climate over the whole face of our globe ; the 



• Mr. W. Smith, in his gcoloj;ical map of Norfolk, has indeed delineated 

 Strumpshaw and Porinj^land hills, as detached outlying masses of the Lon- 

 don bine clay ; but I believe that Mr. Taylor will agree with me in regard- 

 ing this as an error ; for I am not aware that any organic remains have ever 

 been found in these hills, to identify thcni with the formation to which 

 Mr. Snjitii considers them to belong. 



vegetable 



