Vol. 56.] ANNIVERSARY ADDRESS OP THE PRESIDENT. lxXXlii 



proved its presence in East Kent. Since then it has also been 

 found at Ropersole. 



This discovery seems to me most interesting, nothing of the sort 

 having been found in the twelve other borings that have gone deep 

 enough, unless some of the beds in the Dover boring should be 

 classed as Lias. 



At Brabourne there may be some Upper Lias, and certainly both 

 the Middle and Lower divisions are represented, the total thickness 

 being 172 feet. But at Ropersole, to the north-east, the formation 

 is much thinner, consisting of only 3 feet of the Upper division and 

 over 24 of the Middle, with none of the Lower. 



With regard to the Trias we were left in doubt for many years. 

 At Kentish Town, Richmond, Streatham, and Crossness various red 

 rocks were found at the bottom of the borings ; but what their age is 

 we know not. They may be Triassic, or Old Red, or both, with 

 stained Carboniferous thrown in ; though the changing balance of 

 evidence seems to have veered against the first conclusion. We could 

 not then say that the Trias was represented underground in the 

 South-east of England before the time of the Brabourne boring, deep 

 down in which (from about 1876 to 1925 feet) there has been found 

 a conglomerate associated with red-and-grey sandy marls. This 

 conglomerate contains, among other things, pebbles of Carboniferous 

 Limestone, and has much the aspect of the Dolomitic Conglomerate of 

 the West of England, which presumably it represents. The Brabourne 

 boring has an additional interest from this unexpected find, the only 

 one of the sort. 



The Older Rocks. 



We have now done with the Secondary formations, and come 

 to the perhaps still more interesting question of the older rocks 

 beneath. 



Of the Permian there is as yet no evidence, of the Carboniferous 

 not much. The slaty rock at the base of the Harwich boring has 

 hitherto been classed as of Lower Carboniferous age; but later 

 evidence, from the neighbouring borings of Stutton and Weeley, and 

 from Culford, the next nearest, has led some of us to doubt this 

 and to think that this rock may be much older. One has been, 

 somewhat reluctantly, forced to the conclusion that all the bottom- 

 rock in those three more recent borings is pre-Carboniferous, and 

 there is some family likeness in all four cases, as perhaps you may 

 some day hear in more detail. 



