466 Notices of Memoirs — British Association — 



divisions are really parts of one foi'mation, and one result of this 

 geologic wedding is for the inconstanc}^ of one partner to be greatly 

 compensated by the constancy of the other. 



The Lower Greensand has been found in one deep boring only, 

 at Culford, in the western part of the county, where it is repre- 

 sented by 32^ feet of somewhat exceptional beds. This slight 

 thickness prepares us for underground thinning, and in the far 

 east of the county the formation is presumably absent, there being 

 no trace of it at Harwich or at Stutton. 



With the Cretaceous beds we pass from the regular orderly 

 succession of geologic formations ; indeed, it may be said that when 

 we reach the base of the Gault we pass out of the region of facts 

 into the realm of speculation. 



We have come then to perhaps the most interesting problem in 

 the geology of the Eastern Counties, to the consideration of the 

 question. What rocks underlie the Cretaceous beds at great depths? 

 In dealing with this I must ask your patience for frequent excursions 

 outside our special district, and sometimes indeed far away from it. 



Beyond the outcrop of the lower beds of the Cretaceous Series 

 in Cambridgeshire and Norfolk, we find of course a powerful 

 development of the great Jurassic Series ; but the only two 

 recorded deep borings in and near Suffolk that have pierced through 

 the Cretaceous base, at Culford on the north-west and at Harwich 

 on the south-east, show not a trace of anything Jurassic : they pass 

 suddenly from Cretaceous into far older rocks. And here a paper 

 that is to be brought before you must be anticipated, to a slight 

 extent, by adding that the trial-boring at Stutton shows just the 

 same thing — the Gault resting directly on a much older rock, which 

 cannot be classed as of Secondary age. 



There is no need now to discuss the literature of the old rocks 

 underground in South-eastern England : that has often been done. 

 We may take the knowledge of what has been shown by the 

 various deep borings as common property, and may use it freely, 

 without troubling to state the source of each piece of information, 

 and I will not therefore burden this address with references. I had 

 indeed thought of supplementing a former account by noticing 

 the later literature of the subject ; but decided to spare you from 

 the infliction, and myself from the trouble of inflicting ; though 

 it may be convenient to add, in the form of an appendix, a list 

 of the chief papers on the subject that have been published since 

 the question was discussed at length in 1889, in an official memoir 

 on the geology of London, and to supply some omissions in that 

 work. Nor do I propose to make any special criticism of papers on 

 the subject that have appeared of late years ; this is hardly the 

 occasion for controversy, which may well be put off to a more 

 convenient season. Some general remarks, however, I shall have 

 to make after putting the facts before you. 



There are 10 deep borings reaching to old rocks in the London 

 Basin, of which accounts have been published. We find that in 



