14 



HA R D WI CKE ' S SCIENCE-GOSSIP. 



It is well-nigh impossible to form a plan which 

 shall at all approach accuracy, in respect to the 

 strata between Chatham and Dover. With the data 



Richmond Str 

 101m 



Crossness 



1 44 St 



1060 



Fig. 16. — Verticil Scale of Underground Rocks. 



that they represent the strata as they probably occur. 

 There is this to be said, however, that the Coal 

 Search Committee some time ago decided to continue 

 the boring at Chatham, which at that time 

 remained at 945 feet, and also to make a 

 trial boring at Ashford, and there seems a 

 great probability that in this way detached 

 basins containing carboniferous beds may 

 be reached. A great deal, however, 

 seems to rest with chance and good for- 

 tune, since when the old surface is reached, 

 possibly an intermediate outcrop of pre- 

 carboniferous beds alone may be the 

 result. Although I have shown bold lines 

 as representing the trend of . the various 

 beds, they are probably divided through- 

 out their whole lengths into isolated basins, 

 although the general bearing may be such 

 as is here shown. 



At the surface, for the whole distance, 

 we are of course upon the chalk, and this 

 would appear to have throughout a fairly 

 uniform thickness, as well as the lower 

 cretaceous beds, but the succeeding de- 

 posits in these two borings differ from one 

 another, and show that the Wealden beds, 

 which have a known thickness at Dover 

 of 82 feet, and probably considerably 

 more, thin out between that town and 

 Chatham, where the lower greensand rests 

 immediately upon Jurassic rocks. 



In the second boring at Dover, it will 

 be noticed that I have shown the appear- 

 ance of coal at a depth of 1380 feet, that 

 is, at 200 feet deeper than the depth given 

 in the reports of the discovery of coal at 



Up Greensand 

 833 



— -A~HARWICH 

 ^ fB 



Dover 



at command, they might possibly have a direction 

 such as shown in diagram ; but the distance is too 

 great to attempt to claim for the directions shown, 



the Channel Tunnel Works. I have thought it ad- 

 visable to do this, since all the other borings have 

 been shown as being reckoned from one dead surface- 



