398 PEOCEBBINGS OP THE GEOLOGICAL SOCIETY. [April 5, 



torn of the Thanet Beds, though its fragments are in no case green- 

 coated, but contrast strongly with the irregular-shaped green flints. 

 This is the only bed of the sort in the Margate Chalk, which, as 

 aforesaid, contains merely a few nodular flints, so that there is no 

 chance of mistake. 



I have reason to think that this conformity extends to a few 

 miles westward of Canterbur3^ It is all the more extraordinary if 

 the highest Chalk here should turn out, as I have suggested above, 

 to belong to the Middle or Lower and not to the Upper Chalk. In 

 the western part of Kent too (near Woolwich, &e.) the junction of 

 the Thanet Sand and the Chalk is remarkably even in all the great 

 sections, and it is thought that there also the Upper division may 

 have been denuded. 



3. On the Chalk o/BtrcKiNGHAMSHiRE, and on the Totternhoe Stone 

 By William Whitakee, B.A., P.G.S. 



I KNOW of but two short notices of the Totternhoe stone, and the 

 older of these is merely to the eff'ect that " the indurated Chalk 

 Marie is extensively quarried at Totternhoe, in Bedfordshire*." 



Prof. J. Phillips, however, has been led to class this stone and the 

 accompanying marl with the Upper Greensand, his words being as 

 follows: — "In Bedfordshire the Chalk Marl produces a bed of 

 siliceous chalky stone, which may probably be analogous to the 

 firestone of Mesterham (Merstham), in Surrey, which is determined 

 to belong to the Upper Greensand." ***** " It is easy to 

 understand how so variable a mass of sand (the Upper Greensand) 

 placed immediately below the Chalk, and clearly in many places 

 graduating into that calcareous rock, should in several instances be- 

 come so cretaceous as to be hardly distinguishable from the Chalk 

 itself. This happens in Bedfordshire, where the Tattenhoe (Tot- 

 ternlioet) stone appears to be the representative of the Upper 

 Greensandil:. 



I would remark that the name '' Chalk-marl " is, I believe, used 

 strictly for the lowest and more clayey part of the Chalk, and there- 

 fore that bed can hardly be analogous to the Upjjer Greensand 

 which occurs beneath it. 



The mapping of the Upper Greensand in Buckinghamshire gave 

 much trouble to the Geological Survey, and it was only after re- 

 peated visits, by the help of fresh sections, and from a knowledge of 

 a great leng-th of country along the foot of the Chalk ridge, that the 

 difficulty was cleared up, happily, too, without leaving any room for 

 doubt, and the Totternhoe stone and marl were found to overlie un- 

 boubted Upper Greensand. 



The broad distinction of the " Chalk-with-flints " and the " Chalk- 

 without-flints " holds in Buckinghamshire, as in most places ; but 

 the latter consists of many divisions, as shown by the section, though 



* ' Geology of England and Wales ' by the Kev. W. D. Conybeare and W. 

 Phillips, 1822, p. 163. 



t Tattenhoe is the name of another Yillage some miles to the north-west, and 

 on Oxford Clay. 



t 'Manual of Geology,' 1855, pp. 352 & 357. 



