552 



SUCCESSIVE PROCESSES OF DRAINAGE. 



and is forced to pass round the southern extremity of the Long Mountain, before it can 

 unite with the Severn near Welsh Pool. The fact of this sluggish stream, thus feebly 

 wandering, at a very slight inclination, in a country considerably above the sea, points 

 out that a change of level, of a few feet only, must have drained the whole of the ad- 

 jacent low countries from a cover of water j and this view is supported by the fine 

 character of the debris in the Vale of Montgomery, it being very distinct from that of 

 the coarse detritus which has been thrown off the flanks of the adjacent volcanic region 

 of the Cornden Hills. 



Sufficient evidence has now, I hope, been produced to satisfy the reader ; — 1st. That 

 the largest accumulations of gravel throughout this region were formed beneath the sea. 

 2ndly. That after the earliest desiccation of the submarine surface, the newly raised 

 land was, for a long time, in an intermediate state, and in a great measure watered by 

 lakes and broad rivers. 3rdly. That in consequence of successive upheavings of the 

 land, the transverse gorges and fissures have been deepened, by which large volumes of 

 water have been let off; and, lastly, that the sea being further removed by each move- 

 ment of elevation, former estuaries were desiccated, previous strings of lakes reduced to 

 the mere rivers of our day, and the direction of some of the early river courses changed. 

 This view will be further illustrated and sustained by a consideration of the remains 

 of extinct species of quadrupeds which are found in the gravel and in clefts and 

 caverns. 



On the presence of the Bones of Quadrupeds of extinct species in Siluria. 



Among the various methods of establishing the early existence of dry land, none 

 is more effective than the presence of the remains of terrestrial animals of species now 

 extinct. If, as in the present case, such evidence be combined with that of the former 

 existence of lakes, their desiccation, the subsequent deepening of river beds, and the 

 formation of river shingle and gravel during long periods, the proofs are complete 1 . 



the region is to the south-east, has led the country people to say that " the Camlet is the only river in Shrop- 

 shire which runs up hill." 



1 A good example of caves, containing bones of extinct quadrupeds in North Wales, was pointed out by the 

 Rev. Edward Stanley, now Bishop of Norwich. (See Proceedings of the Geological Society, vol. 1. p. 402.) 

 These caves occur in the carboniferous limestone of Cefn, in Denbighshire, at a height of about 100 feet above 

 the present drainage of the country. The remains consist of a humerus of a Rhinoceros, a tooth of a Hycena, 

 and other fragments, and they were covered by and immersed in calcareous loam, containing also a few angular 

 fragments of limestone. Beneath them, and under what the author considered to be the floor of the cave, was 

 another deposit, differing from that above, in containing also fragments of bones and rounded pebbles of old rocks. 

 The evidence which has yet been produced appears to me scarcely adequate to sustain the inference that the 

 cave was inhabited, though it affords satisfactory proof that such wild animals then existed in an adjacent 

 region. It may be objected, that as gravel containing recent species of sea shells (the northern drift) has been 

 found upon the high ground above the cave, that this district may have been inundated by a marine drift, after 



