W. WHlTAKEPv ON SOME BOEINGS IN KENT. 43 



least that a negative one cannot be given ; for we know not what 

 may he hidden under the Jurassic and possibly Triassic beds that 

 have been found ; and Upper Silurian, Devonian, and Lower Car- 

 boniferous rocks having already been found, it would be strange if 

 the Upper Carboniferous had been wholly swept off. 



In reference to water-supply from the Lower Greensand, the 

 dream of many a geologist and engineer, surely there is evidence 

 enough to show that it is not worth any great expenditure, except 

 perhaps on the south of the Thames Yalley and not far from the 

 outcrop. This perhaps may be made more plain by the following 

 tabular statement of the beds found, below the Gault, in the eight 

 deep borings that have been referred to, the only ones in the London 

 Basin that give us this information. The numbers 1-4 refer to 

 sites along an E. and W. line (roughly), whilst the letters A-D refer 

 to those along the lines northward therefrom : — 



Lower Greensand {Neocomian). 

 L Richmond. Yery thin. 

 4. Chatham. Thin. 



C. Ware. Trace (doubtful). 



The Loughton boring may also touch this formation. 



Middle Jurassic. 

 4. Chatham. Not bottomed. 



Lower Jurassic. 



1. E,ichmond. Only 10 feet below the Grault. 



2. Meux's. Next below the Grault. 



Trias ? 



1. Richmond. 



3. Crossness. Next below the Gault. 



A. Kentish Town. Next below the Gault. 



Carboniferous. 



D. Harwich. Next below the Gault. 



Devonian. 



2. Meux's. 



B. Cheshunt. Next below the Gault. 



Upper Silurian. 



C. Ware. Practically next below the Gault. 



From this it follows that (so far as our slender data go) Jurassic 

 beds or Trias are as likely to occur either next to or not far below 

 the Gault as is Lower Greensand, there being three records of each, 

 allowing Loughton to make up for the doubt at Ware. Moreover, 

 the Lower Greensand, where it has occurred, is but thin. The 

 balance of probabilities is therefore against the occurrence of Lower 

 Greensand in the inner parts of the London Basin, and our evidence 

 is decidedly against its presence in fair thickness. This formation 

 may, of course, occur in many places, and in some it may be thick ; 

 but even then there is great chance of its being in i^atches, disconnected 

 with the outcrop, or with but a slight connection. If it anywhere 

 overlaps permeable Jurassic or Triassic beds there may be a water- 



