( 43 ) 



56. — Some Surrey Wells and their Teachings : with Sections 

 OF Wells and Deep Borings in the Surrey Part op 

 THE London Basin. 



By WiLLLua Whitakek, B.A., F.G.S., Assoc. Inst. C.E. 



(Read December 9th, 1885.) 



Since the publication of the Geological Survey Memoir on 

 that part of the London Basin which includes Surrey ^ a great 

 number of additional well-sections in the tract therein described 

 has come into my hands. It was hoped that these might be 

 printed by the Geological Survey ; but, as there now seems little 

 chance of that, I am glad to offer such of the sections as belong 

 to Surrey to the Croydon Microscopical and Natural History 

 Club, in order that they may no longer remain unprinted. 



Amongst them are some old wells, recorded in the MSS. of the 

 late Dr. J. Mitchell, for the use of which I have to thank 

 Professor Prestwich. I have also to thank the engineers, well- 

 sinkers and others who have so kindly given me information. 



In most cases, where details have been preserved, the wells 

 begin in the London Clay (or in some overlying gravel or sand), 

 and are carried through the underlying Lower London Tertiaries 

 into the Chalk by boring ; but in cases the wells begin in lower 

 beds, sometimes in the Chalk. 



The chief geological value of the wells lies of course in the 

 details given of the nature and thickness of the beds passed 

 through ; but, besides this, in many cases we gain information 

 as to the underground water-level, and, to some extent, as to the 

 yield, both matters of no little importance. 



It will be seen that in the great majority of cases the Chalk is 

 aimed at as a source of supply, and in three cases only is a boring 

 carried through that formation. The chief case is atEichmond, and 

 though the section of the deep boring there has but lately been 

 published,^ yet, as it is of great interest and importance, and as 

 the details are scattered through many pages, I have thought it 

 well to collect the whole together and to include it with the 

 unpublished sections. Two formations not before known in the 

 county, and below any seen at the surface in the county, have 

 been found, namely, Great Oolite, and the red rocks, perhaps of 

 Triassic age, in which the boring ends. 



It is not, however, from the occurrence of these two forma- 

 tions that this, the deepest boring in the South of England, is 

 remarkable ; its chief lesson is to enforce the teaching of other 

 deep borings m and near London, namely, the northerly 

 thinning underground of the Lower Cretaceous divisions that 



1 Vol. iv. of the ' Memoirs ' (1872). SuiTey well-sections are described 

 on pp. 537—563. 



-Prof. Judd, Quart. Journ. Geol. Soc, vols, xl., xli. 



