180 Professor W. Boyd Dawhiiis [Juue 6, 



Held and the North Downs, rendered it undesirable to repeat the 

 experiment vvitliin the Wealden area proper, where the Weaklen 

 rocks presented a total thickness of more than 1000 feet, in addition 

 to that of the Oolites. My attention, therefore, was directed to the 

 lino along the North Downs, where Godwin- Austen believed that the 

 Wealden beds abruptly terminated against the ridge of coal-measures 

 and older rocks, and where, therefore, there would be a greater 

 chance of success. 



10. The evidence, also, of the French, Belgian, and Westphalian 

 coal-fields pointed in the direction of the North Downs. 



The Carboniferous and older rocks, which we have hitherto 

 traced only as far as the area of London from their western outcrops 

 in Somerset, Gloucestershire, and South Wales, reappear at the sur- 

 face in Northern France, Belgium, and WeBt23halia, and contain most 

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

 from the district of the Euhr on the east, through Aachen, Liege, 

 Namur, Charleroi, Mons, and Valenciennes. 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 ujDwards of 95 miles away from its disappear- 

 ance under the Oolites and chalk, as far as Flechinelle, south of Aire, 

 or to within 30 miles of Calais. It occupies throughout this distance 

 a narrow trough or syncline, 11 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 dej^th 

 of 1101 feet from the surface, in 1850,* reveal the existence of 

 another coal-field in the same general line of strike, and making fur 

 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 experimental borings, until 

 they have been proved to exist underneath Calais. The opposite shores 

 of the Straits of Dover, therefore, presented the best locality for a trial 

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

 works, close to Shakespeare Clitf, 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 six miles to the south of a spot where about 4 cwt. of 

 bituminous material was found imbedded 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 dealing with the 

 question of a tunnel between England and France, that the older 



* This fact is doubted by Gosselet. I am, however, intbriued by Prestwich 

 that both lie and Elie tie Beaumont identified them as ooal-nicasuies at the time, 

 and I see no reason for doubting the accuracy of those two eminent observers. 

 The cores were, uuibrlunately, lost in the first Paris Exiiibition. 



