July 31, 1890] 



NATURE 



321 



Belgium, and Westphalia, and contain most valuable 

 coal-fields, which are long, narrow, and deep. These ex- 

 tend from the district of the Ruhr on the east, through 

 Aachen, Lidge, Namur, Charleroi, Mons, and Valencien- 

 nes. The enormous value of the last field led, during the 

 last hundred years, to numerous borings through the 

 newer rocks, which have extended the western range of 

 the coal-measures upwards of 95 miles away from its 

 disappearance under the Oolites and chalk, as far as 

 F'lechinelle, south of Aire, or to within 30 miles of Calais. 

 It occupies throughout this distance a narrow trough or 

 syncline, 1 1 miles across at Douchy, and about half a mile 

 at its western termination. It is represented still further 

 to the west by the faulted and folded coal-fields of 

 Hardinghen and Marquise, which are within about 12 

 miles of Calais. The coal-measure shales and sandstones 

 found in a boring at Calais, at a depth of X104 feet from 

 the surface, in 1850,^ reveal the existence of another coal- 

 field in the same general line of strike, and making for 

 Dover and the North Downs. 



(11) We have seen that the range of the coal-measures 

 has been pushed farther and farther to the west by ex- 

 perimental borings, until they have been proved to exist 



underneath Calais. The opposite shores of the Straits o* 

 Dover, therefore, presented the best locality for a tria^ 

 still further to the west. In choosing a site, the Channel 

 Tunnel works, close to Shakespeare Cliff, Dover, appeared 

 to me to present great advantages, which I embodied in 

 a report to Sir Edward W. Watkin, in 1886. The site is 

 within view of Calais, and not more than 6 miles to the 

 south of a spot where about 4 cwt. of bituminous material 

 was found embedded in the chalk in making a tunnel, 

 which, according to Godwin-Austen, had been probably 

 derived from the coal-measures below, 



Prestwich also had pointed out, in 1873, in deahng with 

 the question of a tunnel between England and France, 

 that the older rocks were within such easy reach at Dover, 

 that they could be utilized for the making of a submarine 

 tunnel. Sir Edward Watkin acted with his usual energy, 

 and the work was begun in 1886, and has been carried on 

 down to the present time, under my advice, and at the 

 expense of the Channel Tunnel Company. The boring 

 operations have been under the direction of Mr. F. 

 Brady, the Chief Engineer of the South-Eastern Railway, 

 to whose ability we owe the completion of the work to its 

 present point, under circumstances of great difficulty. A 



Coal Measure.x. 



A Borinq. 



B.Channel Tunnd Shaft- 



Fig. I. — Boring at Shakespeare Cliff. 



shaft has been sunk (a. Fig. i) on the west side of the 

 Shakespeare Cliff, close to the shaft of the Channel 

 Tunnel (b) to a depth of 44 feet, and from this a bore-hole 

 has been made to a depth of 11 80 feet. 



Section at Shakespeare CliJ^, Dover. 



Lower grey chalk, and chalk marl 



Glauconite marl 



Gault 



500 



660 



Neocomian 

 Portlandian 

 Kimmeridgian 

 Corallian ... 

 Oxfordian... 

 Callovian ... 

 Bathonian 



Coal-measures, sandstones, and shale sand clays, \ 

 with one seam of coal J ' 



The coal-measures were struck at a depth of 1204 feet 

 from the surface, or 1160 feet from the top of the bore- 



' This fact is doubted by Gosselet. I am, however, informed by Prest- 

 wich that both he and Elie de Beaumont identified them as coal-measures 

 at the time, and I see no reason for doubting the accuracy of those two 

 eminent observers. The cores were, unfortunately, lost in the first Paris 

 Exhibition. 



NO. 1083, VOL. 42] 



hole, and a seam of good blazing coal was met with 20 

 feet lower. 



(12) This discovery proves up to the hilt the truth of 

 Godwin-Austen's views as to the range of the coal- 

 measures along the line of the North Downs, and as to 

 the thinning off of the Oolitic and Wealden strata against 

 the buried ridge. The former are less than one-third of 

 their thickness at Netherfield, and the latter are wholly 

 unrepresented. It establishes the existence of a coal-field 

 in South-Eastern England, at a depth well within the 

 limits of working at a profit. The principal coal-pits in 

 this country are worked at depths ranging from over 1000 

 to 2800 feet, and one at Charleroi, in Belgium, is worked 

 to a depth of 3412 feet. 



The Dover coal-field probably forms part of the same 

 narrow trough as the Calais measures, prolonged west- 

 ward under the Channel further to the south than 

 Godwin- Austen drew it in 1858. Whether it is a trough 

 similar to that which extends through Northern France 

 for more than 100 miles from east to west, as Godwin- 

 Austen has drawn it in the diagram on the wall, reaching 

 as far to the west as Reading, or whether it is a small, 

 faulted, insignificant fragment of a field, such as that of 

 Marquise and Hardinghen, remains to be proved. It is, 



