1894 NOTES AND COMMENTS. 333 



Fishing for Coal at Calais. 



Nearer home there is another source of wealth that has long lain 

 unworked because unknown, namely the beds of coal that are now 

 believed to underlie the south-east of England. We have lately 

 received important information bearing on this subject. 



Stimulated by the discovery of coal at Dover, our neighbours 

 across the Channel bethought themselves, some time since, to make 

 a forage near Calais. The proximity of the small coal-field in the 

 Boulonnais, and the circumstance that the spot selected for the experi- 

 ment was practically on the line of strike of known productive Coal- 

 measures, were also factors greatly in favour of the undertaking. 

 The results, although interesting from a scientific standpoint, are not 

 altogether encouraging in the commercial sense. For we learn that 

 at a depth of 325 metres the boring tools have entered rocks of 

 Devonian age, as proved by the occurrence of fossils. 



Mr. Gustave Dollfus, of the Geological Survey of France, who 

 has carefully watched the progress of the work since its commence- 

 ment, is of opinion, we are informed, that these Devonian rocks are 

 inverted, notwithstanding the fact that they are horizontal. Judging 

 from the disposition of the upper Palaeozoic rocks along the axis of 

 the Ardennes from the neighbourhood of Liege, through Namur 

 and Mons to their underground prolongation into the Pas de Calais, 

 it would seem that Mr. Dollfus possesses sound arguments in favour 

 of his hypothesis, though he has not yet put them forward. In the 

 last-mentioned locality, as at Liege, the Coal-measures are found 

 beneath the Devonian. The Palaeozoic beds concerned are much 

 faulted, folded, and at places inverted. These phenomena appear to- 

 have been caused by the influence of a force which acted in a 

 direction from south to north, while the chief disturbances resulted in 

 the formation of oblique faults. The most important of these is the 

 great Eifelian fault which bounds the main coal-basin on the south. In 

 many places the Lower Devonian of the basin of Dinant, abutting 

 against the ridge of Condroz, has been thrust over the coal beds of 

 the Namur basin, and this together with the inversion of the Middle 

 and Upper Devonian, Carboniferous Limestone, and part of the Coal- 

 measures themselves has much complicated the stratigraphy. 



In these conditions it would be perfectly possible to find the Coal- 

 measures at Calais under either inverted or normally-disposed 

 Devonian, though had the boring been situated rather more to the 

 south, the probabilities would, in our opinion, have been greater. When 

 other borings than the one near Dover reach Palaeozoic rocks irL 

 Kent, we shall not be surprised, therefore, to learn that these latter 

 are Devonian, and the discovery of beds of that age in the London 

 area does not altogether do away with the. possibility of the 

 occurrence of Coal-measures in the neighbourhood of the metropolis. 

 It has long been recognised by geologists that the old Palaeozoic floor, 

 or " ridge," under London has much in common with the axis 

 of the Ardennes. 



