W. WHITAKER ON SOME BORINGS IN KENT. 47 



is more irregularity, and even that there may be abrupt disappear- 

 ance in some cases : as, however, we don't know the exact sites of 

 disappearances, it would clearly be hazardous to mark any such 

 occurrence strongly. 



Judging by the deep borings in and near London, and by the 

 Harwich boring, one would expect that the Oxford Clay does not 

 range to a great distance northward from Chatham ; and therefore, 

 some miles in that direction, the section has been made to agree 

 with what happens near London, where the Gault next overlies 

 beds of various ages, but all older than Oxford Clay. These beds 

 have been massed together. 



EXPLAlfATION OF PLATE III. 



The Plate has been made from the original section, which was of the scale of six 

 inches to a mile, horizontally and vertically, by reduction to a sixth, or an inch 

 to a mile, horizontally, and to a third vertically. The vertical scale, therefore, 

 is 2640 feet to an inch, and being only exaggerated to double the horizontal 

 scale, there is, practically, no distortion. The reduction has been made by 

 Mr. J. Gr. Goodchild, of the Geological Survey. 



The horizontal scale being the same as that of the general Ordnance Map, 

 and the line of section being expressed on the Geological- Survey version of that 

 Map, it will be easy for any one possessing the latter map, and not very diflS- 

 cult for possessors of the former only, to follow the course of the section. 

 This course, and the data on which the underground range of the beds has been 

 shown, to great depths, have been noticed above. 



Discussion. 



Prof. Presiwich remarked on the great value of the communi- 

 cation. He agreed that there was little hope of finding water in 

 the Lower Green sand at great distances from the outcrop of that 

 formation. With respect to the finding of the Coal Measures, he 

 thought that somewhere in the district between the Thames, near 

 Chatham, and Harwich were the places where they might most pro- 

 bably be found. He pointed out how analogous the succession of 

 strata between Boulogne and the Palaeozoic rocks of the Boulonnais 

 was to that between the Battle boring, Chatham, and Harwich. 



Mr. Etueridge said that the different borings were of very con- 

 siderable interest, taken in connexion with the facts previously 

 known. 



Mr. ToPLEY pointed out that the existence of the Oxford Clay 

 beneath the South-east of England had been correctly inferred from 

 the abundance of derived Oxfordian fossils in the Lower Greensand. 

 He agreed with the author as to the previous under-estimatc of the 

 thickness of the Gault. He thought the borings lent some support 

 to the view that the upper part of the Folkestone Beds belongs to 

 the Gault rather than to the iS'eocomian. 



Mr. Easton did not think the Lower Greensand aff'orded a suffi- 

 cient gathering-ground for water-supply. He doubted if the Coal 



