670 REPORT— 1895. 



tliat geologists are coming to the conclusion that these two divisions are really 

 parts of one J'ormation, and one result of this geologic wedding is for the in- 

 constancy of one partner to be greatly compensated by the constancy of the 

 other. 



The Loiver Greensand has been found in one deep boring only, at Culford, in 

 the western part of the county, where it is represented by 32i 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 geo- 

 logic 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 sjieculation. 



We have come then to perbap«i the most iaterestiiig 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 Cambridge- 

 shire 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 directlj' 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 thei'efore burden this address with references. I had indeed thought 

 of supplementing a former account by noticing the later litei'ature of the subject; 

 but decided to spare you from the infliction, and myself from the trouble of inflict- 

 ing ; 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 dis- 

 cussed at length in 1889, in an official memoir on the geology of London, and to 

 supply some omissions in tliat work. Nor do I propose to make any special criti- 

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

 occasion for controversy, which mav well be put oft' 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 4 of these (Meux's, Streatham, 

 Ilichmond, and Dover) Jurassic beds separate those rocks from the Cretaceous beds; 

 so that there are 6 in which these last rest direct on old rocks (Ware, Cheshunt, 

 Kentish Town, Crossness, Culford, and Harwich). Stutton of course makes a 

 seventh. The Jurassic rocks occur only in the southern borings, either in London 

 or still further southward, and in one case only (Dover) is there any considerable 

 thickness of these : in the other .'J they are from 2>&^ to 87^ feet thick. As far 

 as regards Suffolk and its borders we may therefore disregard them, except in the 

 far west, near their outcrop, and we may pass on to consider the older rocks that 

 have been found. 



So far the occurrence, next beneath the Cretaceous or Jurassic beds, of Silurian, 

 Devonian, and Carboniferous rocks has been proved, whilst in some cases we are 

 still doubtful as to the age of the old rocks found. In 5 cases distinctive fossils 

 have been found (Ware, Cheshunt, Meux's, Dover, and Harwich), but in 5 others 



