ANNIVERSARY ADDRESS OF THE PRESIDENT. 



231 



been solved (at present at least) ; had the Lower Greensand oc- 

 curred in its normal condition as a water-bearing stratum, or even 

 had the Upper Greensand (above the Gault) yielded water in quan- 

 tity, neither at Messrs. Meux's, at Turnford, nor at Ware should we 

 have touched the undoubted and unequivocal Devonian and Silurian 

 strata. Eew give thought to or are aware of the difference that 

 exists in the thickness of rocks of the same age in different yet not 

 very remote localities. In Britain the Cambrian and Lower Silurian 

 deposits are from 20,000 to 30,000 feet in thickness, whilst in 

 Sweden and Russia their representatives or equivalents in time 

 rarely if ever exceed 1000 feet. 



This difference is and was probably due to the form and nature of 

 the Pre-Cambrian land on which the newer Cambrians and Silurians 

 were deposited ; for there cannot be any doubt that such Pre- 

 Cambrian rocks did and do exist, and were and are widely extended, 

 although concealed over the present known European area, and that 

 their existence was connected with a probable great geographical ex- 

 tension westwards of the British Islands. The plateau governed by 

 the 100-fathom level that surrounds the British Islands is part of 

 this extension, on which all our physical changes have taken place. 

 Probably the crystalline rocks of Scandinavia, parts of North Wales, 

 North-west Ireland, St. David's, and the Hebrides are exposed areas 

 of this Pre-Cambrian stage of the highest antiquity, and were covered 

 on their submerged and denuded masses by the Longmynd, Harlech, 

 :id St. -David's rocks, which in their turn were succeeded in 

 some areas by the Lingula-flags, the Tremadoc, and Arenig, life- 

 groups of antiquity so high that we have no formula to express their 

 age, or when life first appeared in the seas of the British Islands. 

 As yet we have no evidence relative to these formations occur- 

 ring eastward of the Penine chain, of which Charnwood, Ashby- 

 de-la-Zouch, and the Warwickshire coal-field are the most southerly 

 exposures ; but we have lately unexpectedly determined the presence 

 of the Carboniferous Limestone below Northampton at the depth of 

 890 feet*. This has carried still further south the Penine axis, 

 and would lead us to expect that between Northampton and the 

 exposed Coal-measures of Atherston and Nuneaton an extended coal- 

 field may occur. What relation the Burford coal on the south may 

 have is conjectural only ; but I am disposed to regard the whole as 

 one greatly extended coal-tract. We must now regard the Carbo- 

 niferous Limestone of Northampton in longitude 1° 30' W. as the 

 most easterly known in England ; and no Triassic rocks cover this 

 limestone, a few feet only of undeterminable rocks occur between it 

 and the Lower Lias f . Whether the New Red has thinned away entirely 

 here, or it happens to be accidentally absent, is a question ; but at 

 Burford on the same strike and relative position there is a consider- 

 able thickness of Triassic rocks, and to the N. and N. W. also every- 



* In the cores brought up I determined the presence of Lithostrotion junceum 

 and Lonsdaleia floriformis in abundance. 



t The cores brought up are 15 inches in diameter. This great undertaking, 

 as well as those at Turnford and Chatham, were carried on by Messrs. Docwra 

 and Grulland with their new machinery. 



