412 Herbert A. Baker — Denudation of the Chalk. 



character Avhich it seems to me would be out of place in a typical 

 Miocene deposit. 



Leaving on one side the northern species which appear to have 

 been more or less suddenly introduced into the Crag basin under the 

 influence of the tectonic depression alluded to, and counting 

 specimens rather than species, there is a general resemblance 

 between the fauna of the Coralline Crag and that of "Walton which 

 does not exist between those of the former and of Lenham. For 

 zoological as well as for stratigraphical reasons I draw the line 

 separating the Lower and the Tipper Pliocene divisions of the East 

 Anglian deposits between the Coralline Crag and the Lenham beds 

 rather than between the former and the "Waltonian. 



I agree to some extent with Mr. Newton as to the age of the block 

 of fossiliferous limestone described by him in 1917.^ From a very 

 superficial examination I formed a strong impression that it was 

 . pre-Pliocene, but I cannot admit, on the other hand, that it has 

 anything to do with the Coralline Crag. It reminded me of some 

 fossiliferous blocks which some years ago Mr. Yan Watenschoot van 

 der Gracht informed me were occasionally dredged in the North Sea. 

 He seemed at that time to be under the impression that they were of 

 Oligocene age.* I believe a collection of fossils had been made from 

 them which were then at The Hague. Hereafter it may be possible 

 to compare these Dutch specimens with those identified by 

 Mr. Newton. It seems not unlikely, moreover, that the latter may 

 be of a similar character to those found by Mr. Norregaard in some 

 erratic boulders of Middle Miocene age obtained from a glacial clay 

 near Esbjerg,^ but this could be probably ascertained without much, 

 difficulty. 



Although I do not agree with the classification adopted by 

 Mr. Newton, I welcome his recent papers as calling attention to an 

 important series of deposits in which formerly much interest was 

 taken, but of late years have been almost entirely neglected. 



V. — On Successive Stages in the Denudation oe the Chale: in 



East Anglia. 



By Heebeet Aethue Bakee, B.Sc, F.G.S. 



4 EECENT attempt by the writer* to utilize the information at 

 Xa. present available with a view to gaining some notion of the 

 dominant characteristics of the denudation suffered by the Chalk of 

 the London Basin prior to the deposition of the Eocenes yielded 

 results of sufficient interest to encourage him to apply the same 

 method of analysis to the East Anglian area. 



Sufficient data for the construction of a provisional map showing 

 the isopachyte system of the Chalk of this area lie to our hand, 



^ Quart. Journ. Geol. Soc, vol. Isxii, p. 7, 1917. 



^ I understand that there is some difference of opinion among Continental 

 geologists as to the correct division between the Oligocene and Miocene of 

 Northern Europe. 



^ Danm. Geol. Undersogelse [4], No. 5, p. 58, pis. i-iii, 1916. 



* Baker, Geol. Mag., July, 1918, pp. 296-305. 



