Profeswr W. Boi/d Daiclcins — The S.E. Coalfield. 503 



depper. Here only two unimportant seams have been met willi 

 in a thickness of 192 feet. There twelve seams were penetrated 

 in a thickness of 1,064 feet 6 inches, the thickest 4-teet seam being 

 at the bottom. 



Tlie Ropersole boring establishes the fact that the Dover coal- 

 measures extend northwards for a distance of eight miles and beyond 

 in the direction of Canterbury. 



It remains now to see how far the range of the South-Eastern 

 Coalfield has been proved by other borings. None of the three 

 others which are now being carried on by the Kent Coal Exploration 

 Company at Ottinge, Hoth field, and Old Soar to the north of 

 Tonbridge has been carried deep enough to give any evidence. We 

 are, however, indebted to Mr. Etheridge ' for conclusive proof that 

 its south-western boundai-y does not extend as far to the south-west 

 as BraboLirne. Here a fine-grained gre}' argillaceous sandstone, in my 

 opinion Devonian, was struck in a boring at a depth of 1,921 feet 

 5 inches from the surface, the strata being inclined at a high angle, 

 and being covered by a red dolomitic conglomerate of Triassic 

 age, just as similar rocks occur in the central axis of the Mendip 

 Hills. This boring has verified the exact position of the Pembroke- 

 Mendip anticlinal fold, which I mapped in 1894.^ It ranges in 

 a north-west and south-easterly direction close under the line of 

 the Chalk downs from Folkestone to Wye, a few miles to the north 

 of the theoretical line of my map, and forms the southei'n boundary 

 of the South-Eastern Coalfield. In Somersetshire it emerges from 

 beneath the Triassic and Jurassic strata in the Mendip Hills, and 

 in Northern France along the low hills sweeping from Hardinghen 

 past Ferques in the direction of Cape Gris Nez, wrhere, as in the 

 Mendip range, it is traversed by many faults. 



The Coal-measures set in in Kent at a sufficient distance to the 

 north-east of Braboui-ne to allow of the presence of the Carboniferous 

 Limestone and Millstone Grit. These probably dip at the same 

 high angle as the Devonian below. Their south-western boundary 

 can only be accurately defined by further borings such as that 

 which we are now carrying on at Ottinge, about two and a half 

 miles to the north-east of the scarp of the Downs, and six miles to 

 the south-west of Bopersole. Their range to the north and the east 

 still remains to be proved. They are, however, continued under 

 the Channel, and have been proved by the boring at Calais in 185U, 

 as well as those carried out in 1898 at Strouannes near Wissant. 

 In this district they are clearly shown by other borings to be faulted 

 into the Devonian and other pre-Coal-measure rocks. 



The thickness and value of this South-Eastern Coalfield can only 

 be estimated by the exposed coalfields of Northern France and 

 Belgium and of Somerset. That of Liege is 7,600 feet thick and 

 contains eighty-five seams, presenting an aggregate thickness of 

 212 feet of workable coal. That of Mons is 9,400 feet, with 110 



1 Brit. Assoc. Bristol Meeting, 1898. 



' "The Probable Range ot the Coal-measures in Southern England" : Trans. 

 Federated Institution of Mining Engineers, vol. vi, map. 



