200 



ME. W. WflTTAKER, OIST THE RESULTS 



slightest difference between them, and in no case was there any 

 notable distinction. We may fairly conclude therefore that this part 

 of the Dover section should be classed with the Sandgate Beds, as 

 ■ was done in the Chatham case. 



Whilst at Chatham, however, these compact clayey sands are 

 overlain by looser sand, like that of the Folkestone Beds, at Dover 

 the upward continuation of the Lower Greensand is still in clayey 

 sands, though differing in colour from those alluded to above, and 

 there seems to be nothing representative of the sandy Folkestone 

 Beds. It seems fair therefore to conclude that we have here the 

 Sandgate Beds alone, especially as these are thicker at the neigh- 

 bouring outcrop than to the west, although that division of the 

 Lower Greensand is the most inconstant of all along the outcrop in 

 Kent, as well as in Surrey. 



Returning to the beds below the Lower Greensand, a little mistake 

 in the published account should be put right. A very small speci- 

 men of one of the clays is described as " mixed with chalky matter." 

 It contained some white specks, which, from their appearance, were 

 taken to be calcareous. When the larger and better set of specimens 

 was examined, this was found to be a wrong inference ; for the 

 peculiar white earth, of which there was plenty, gave no sign of 

 effervescence when dilute hydrochloric acid was poured on it : the 

 acid simply soaked in. 



On a like test being applied to various Cretaceous and Jurassic 

 marine clays a very different result followed : as would be expected, 

 they all gave clear signs of containing calcareous matter. 



In view therefore of the possibility of these clayey beds being of 

 Wealden age, a possibility which had been already alluded to, it 

 was desirable to examine specimens of Wealden clays. Unluckily 

 our rock-collection at Jermyn Street was very poor in this particular, 

 and it was not until after some time that I was able to make the 

 needful examination. 



It having occurred to me that Mr. G. Maw was likely to have a 

 good collection of clays, I applied to him, and he was kind enough 

 to send me twenty-two specimens from Wealden beds. These may 

 be divided into three sets. 



Firstly, three specimens of Weald clay. One of these was from 

 a Paludina -bed, another was from a bed that rested on the Horsham 

 Stone, and the third came from between layers of that stone. Under 

 these circumstances it is not surprising that, in all, effervescence 

 ensued on the application of hydrochloric acid. 



Secondly, eight specimens of Wealden clays from Dorsetshire, 

 none of which caused effervescence. As, however, these were not 

 like our Dover clays, we may pass them by. 



Thirdly, ten specimens from the Ashdown Series, at and near 

 Hastings. These showed various points of likeness to the bottom 

 beds of the Dover boring : none of them caused effervescence with 

 hydrochloric acid ; some of them had the same whitish colour and 

 the same very fine texture ; altogether they reminded one of the 

 Dover specimens, and I feel no doubt that the beds there reached 



