636 Mr. Aubrey Strahan [March 17, 



it is known as the Axis of Artois. Its direction, so far as it is 

 observable, would carry it under the south of England : and that it 

 does take this course is probable, but there are reasons for thinking 

 that the Kent coal-field may lie on the north side of the belt and not 

 in it. 



The map forming Fig. 5 has been prepared to illustrate this 

 point. It extends from Liege to AYest Pembrokeshire, and on it are 

 distinguished visible and proved concealed coalfields. The course 

 of the belt is marked by a long line of narrow coalfields, both visible 

 and concealed. It coincides for some distance with the valley of the 

 Meuse. Then, turning north-westwards, it passes by Bethuue to the 

 neighljourhood of Calais, and, if prolonged, would pass under the 

 English coast near Folkestone. The disturbances of the palaeozoic 

 rocks along the belt are for the most part concealed by a blanket of 

 Secondary and Tertiary strata, but by taking advantage of occasional 

 exposures at the surface through the blanket, but still more by 

 mining operations of great daring and skill, it has been shown that 

 they are of a remarkable character. The strata have not only been 

 thrown into the form of a trough, in which the coal measures have 

 been preserved, but the trough has undergone deformation on a vast 

 scale. So intense have been the earth movements that the southern 

 margin of the trough has been doubled over, older formations have 

 been pushed bodily over the coal measures, and the coal measures 

 themselves have been thrown into complicated folds. There are 

 places where a single vertical shaft may pass through Silurian and 

 Devonian rocks, and under them into carboniferous limestone, and 

 then into coal measures, all upside down. 



The Kent coal-field shows no such structures. So far as can be 

 judged by boreholes, the dip of the coal measures is generally gentle. 

 Faults are certain to exist, though nothing is yet known of them, 

 but there is no reason to suspect the existence of structures com- 

 parable to the gigantic dislocations of the Continental trough. It is 

 difficult to suppose that those huge disturbances tamely die away in 

 a gentle fold within the limits of Kent. 



Some light is thrown on tJiis question by the discovery of the 

 Belgian coal-field of La Campine. About the year 1901 this coal- 

 field was proved by boring through Tertiary and Secondary strata, 

 and upwards of a dozen shafts were being sunk to it when the War 

 broke out. So far as it has yet been explored, the coal-field branches 

 off in a north-westerly direction from the disturbed belt in which the 

 previously known coal-fields are entangled (Fig. .5). It lies on the 

 northern side of the belt, and does not share in the intense folding 

 and overthrusting which characterize the belt. It seems not 

 improbable, therefore, that the Kent and the Campine coal-fields 

 may be comparable both in their general structure and in their 

 relations to the belt of disturbance. If this be so, the continuation 

 of the belt may be expected to lie south of the Kent coalfield, 



