388 Mackintosh — On the Cliffs and Valleys of Wales. 



might be regarded as unsatisfactory indications of raised coast-lines, 

 situated chiefly, though not exclusively, on the east or Eadnorshire 

 side of the Wye. Whatever amount of erosion the river may pos- 

 sibly have accomplished in pre-glacial times, these cliffs, and sub- 

 jacent drifts, render it certain that it has not flowed above the level 

 of its gravel banks since the occupation of the valley by the sea. 

 But before proceeding to describe the cliffs in detail, it may be well 

 to try to dispose of an apparent objection to the idea of their being 

 in reality old sea-margins. Generally speaking (not always) the 

 platforms coincide in inclination with the outcrop of the strata which 

 here mainly dip at a small angle to the N.N.W., or contrary to the 

 fall of the river-channel. This fact (which, coupled with others, 

 furnishes a strong presumption that neither the river nor a valley 

 glacier could have had any share in the formation of the cliffs) can, 

 I think, be sufficiently explained by the very probable supposition 

 that the original correspondence between the horizontality of the 

 outcrop of the strata and the sea-level may have been the reason 

 why here and elsewhere su.ch a succession of regular terraces should 

 have been formed, while, under less favourable conditions, the sea 

 failed to carve out very distinct coast- lines. But if these rocks can be 

 shown to be sea-cliffs by a strict application of that analogical in- 

 duction on which the whole superstructure of geology as a science 

 is founded, then such seeming difficulties as the above may be left 

 out of consideration. 



The Abereddw cliffs consist of Ludlow rocks of varying compact- 

 ness, the hardest often forming their base. They run along the side 

 of the valley for at least half-a-mile. There are four principal lines 

 of cliff, with several subordinate ones, the latter apparently worn 

 back at intervals so as to merge into the principal. At their northern 

 termmation they are separated from a single lofty cliff by a dry inlet, 

 the sides of which present cliffs of the same form as those frontiug 

 the valley. The existence of this inlet, the floor of which rises up 

 obliquely to the planes of stratification, is, at the very outset, a fatal 

 objection to the theory that the cliffs have been formed by the atmo- 

 sphere, and it is equally inexplicable by river-action. On the north- 

 side of this inlet there are several pillars which present a smoothed 

 outline very distinct from any shape communicated to the rocks by 

 weathering (see Plate XV. Fig. 2). Beyond the upper termination of 

 this inlet the left-hand line of cliff is continued, and here and there 

 its base exhibits small caves, beautifully smoothed and rounded in 

 a way that streams of fresh water (supposing them ever to have been 

 here) could never have accomplished. At the base of the lowest 

 main line of cliff, and at perhaps fifty feet above the railway, there 

 are several caves with arched entrances. In one cave two lateral 

 openings communicate with the main entrance ; and on one side of 

 the latter a pier only a few inches in diameter supports the super- 

 incumbent fabric. The interior of this cave is here and there rounded 

 and smoothed in a way as much resembling modem marine architec- 

 ture as a ripple-marked slab of sandstone is like ripple-marked sand 

 on the sea-coast. If the first is not the work of the sea, neither is the 



