40 W. WHITAKEE ON" SOME BOEIIs"GS TK KENT. 



added from the result of the Subwealden Boring, shortly to be 

 referred to. 



D. General Eemaeks on the Deep-seated Geology oe the 

 London Basin. 



The facts of the Chatham borings being now before us, it may be 

 profitable to compare them with those of the other deep borings in 

 the London Basin, and to see whether the evidence of this sort now 

 in the hands of geologists warrants any general conclusions as to 

 the deep-seated stratigraphy of that large district. Firstly, let us 

 take those borings along the Valley of the Thames, westward of 

 Chatham, and then, having seen what occurs along this E. and "W. 

 line, examine the evidence to the north and to the south, in all 

 cases beginning below the Gault, down to which point there is 

 regularity. 



The furthest boring westward of Chatham is that at Eichmond, 

 which has lately been described to the Society by Prof. Judd*, and 

 is about 37 miles distant. Here we find 10 feet of beds which are 

 probably IN'eocomian, whilst the Lower Greensand at its outcrop, 

 fifteen miles or more to the south, is about 400 feet thick. To this 

 succeeds 87 feet of Jurassic limestone, with clay, but of Great Oolite 

 age; so that the whole of the Wealden Beds are here absent, 

 as at Chatham, and also the Upper and Middle Jurassic (in the 

 latter of which the Chatham boring ends). The Lower Jurassic 

 beds are succeeded by what seems to be Trias, in which the boring 

 ends at a depth of 1447 feet, the greatest reached in the London 

 Basin. 



Nine miles north-eastward we come to Meux's Brewery, where 

 there is no trace of Lower Greensand, but only 64 feet of Jurassic 

 limestone &c. (of the same age as that at Richmond) between the 

 Gault and the Devonian shale, in which the boring ends. 



In the Kentish-Town boring, about 3 miles to the north, the 

 Gault is succeeded by a set of beds that may be Trias, though some 

 geologists take them to be Old Bed ; and, as at Richmond, these 

 possibly Triassic beds were not bottomed. 



Over 11 miles further east from Meux's, at Crossness, a like 

 thing occurs, the Gault being underlain by red beds, perhaps ot 

 Triassic age. 



With regard to the argument against the red beds at Richmond 

 being classed as Trias, from the fact that "nowhere else did an un- 

 conformity so marked occur between Oolitic and Trias," brought 

 forward by Prof. Hughes in the discussion on Prof. Judd's paper f, 

 one may remark that it applies only to the Richmond section, where 

 the red beds are overlain by a Jurassic deposit. It does not apply 

 to the cases of Kentish To^^n and Crossness, where the Gault comes 

 next to the red beds. As, in the West of England, Cretaceous beds, 

 overlapping the whole of the Jurassic Series (including the Lias), 



* Quart. Journ. Geol. Soc. vol. xl. p. 724, vol. xli. p. 523. 

 [ Quart. Journ. Greol. Soc. vol. xl. p. 763. 



