ancient sea-beaches. Between each one of these hills runs North and South a 

 deep valley, conveying the drainage of the IVIillstone Grit plateau to the sea, 

 and serving as an outlet to the shipping ports of the mineral treasures of the 

 Coal-basin. The extraordinary feature of these vaUeys is their extreme regu- 

 larity and similarity, and apart from their mineral value, they are full of beauty. 

 The mountains rise on each side with great steepness, lea\dng at the bottom just 

 room for the river, which is usually fringed in the most charming manner with 

 wild overhanging woods. The native quiet and isolation of these valleys is 

 considerably spoilt by the railways which run up every one of them, but even 

 now there is sufficient beauty to attract the tourist, who, however, very seldom 

 penetrates these unknown districts. From Pontypool to Aberdare, parallel 

 valleys are exceedingly regular, those of the Afon, the Ebbw, the Sirhowy, and 

 the Ehymney converging to the port of Newport ; the Taflf, with its subsidiary 

 valley of the Cynon, the Dare, the Bargoed Taff, the Khondda, and the Ely 

 finding their outlet at Cardiff. Westward the Ogmore and the Llynvi run down 

 to Porthcawl, the Neath and the Corrwg to Briton Ferry and Neath, the Tawe 

 to Swansea, the Lloughor to Llanelly, and the Gwendraeth to Kidwelly. How 

 then do we account for these valleys, and the general configuration of the Coal- 

 basin ? I believe that the Coalfield was the subject of the following movements, 

 and although I am aware that my views may be objected to on several points, 

 I cannot come to any other conclusion, after many years' study of the district. 

 I consider that the first great epoch was — 



1.— The deposition of the Lower Beds (the basin being divided, as we shall 

 see further on, into Lower and Upper beds). 



2.— Their subsidence— and so far the South Wales field has the same 

 geological history as any other Coal field. 



3. —The occurrence of a great westerly force. 



Many eminent geologists, including Sir Henry De la Beche, advocated 

 this theory, which certainly seems to me to account for a great deal of both 

 outward and inward formation of the Coal basin. Suppose we take a plain even 

 surface of clay or mud, enclose it in a box, and then apply an unequal pressure 

 at the side, what would be the result ? Why, just such a crumpling up and 

 folding of strata as we see here before us. There will be miniature parallel hills 

 and valleys on the surface of the clay, just as there is in the Coal field. Sir H. 

 de la Beche considered that this force, whatever it was, had its greatest intensity 

 at some point in what is now St. George's Channel, between Wales and 

 Ireland. If we drop a stone into water we see that concentric waves are formed, 

 decreasing in intensity as the distance from the disturbance increases. Now, 

 this is just what we see in the Coalfield. In Pembrokeshire (which would be 

 the nearest point to the disturbance) we have the coal strata contorted and 



k disarranged ; we have the occurrence of Trap Backs, the only point any where 

 near the coal field where they occur, and we have the concentrated anthracitic 

 tendency showing itself all over the Lower Measures ; this anthracitic character 



