﻿Modern Attainments in Geology. 283 



the river Shannon, we again meet with the overthrust 

 edge of a series of folds. This overthrust edge stretches 

 directly across the southern part of Ireland, reaches 

 Wales at St. Bride's Bay, and passes straight across 

 the southern peninsula of Wales, through the coal fields of 

 Glamorgan, directly across the Bristol Channel to the 

 Mendip Hills, then, covered by more recent sediments, 

 across the south of England to Calais and the district 

 of Douai and Valenciennes in the vicinity of the boundary 

 between France and Belgium. The overthrust is here 

 very well known, because just on this line in France are 

 important deposits of coal ; they are all more or less 

 inverted. The strike of this outer edge and the corre- 

 sponding folding is in an easy curve from west-north-west 

 to east-south-east. 



Everything lying to the south of this line, that is Kerry 

 and Cork, Cornwall and Devon, Normandy and Brittany, 

 as far as Vendee, is made up of folds of the same direction 

 of strike ; they were all folded towards the north and later 

 broken down, that is, divided up into horsts. It may also 

 be here remarked that the geological age of this system of 

 folds is known and that it is less than that of the 

 Caledonian. The time of principal folding falls in the 

 later part of the Carboniferous age, because the older 

 members of the coal formation have been concerned in the 

 folding, while the younger members overlap the already 

 denuded folds. We therefore designate the age of this 

 folding as intercarboniferous. The highest mountains of 

 this system seem, as far as we can judge from the 

 remaining fragments, to have been in Brittany, perhaps in 

 Morbihan ; and as the peninsula of Brittany was called by 

 the Eomans Armorica, we call this system of folds the 

 outer edge of which, as already stated, ran from the 

 Shannon to the Franco-Belgian boundary, the Armorican 

 folds or the Armorican mountain system. 



Beginning at the point just mentioned, between Douai 



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