126 PROF. W. BOYD DAWKTNS OX A PLIOCENE [May I903, 



VII. The Denudation op the District since the Pliocene Age. 



I pass now to the question of the denudation of the district since 

 the cave was filled in the Upper Pliocene Age. In my work on 

 ' Early Man in Britain' (p. 144), I pointed out that the absence of 

 Pliocene caves in Europe was due to the fact that the whole of the 

 Pliocene surface had been denuded away from the areas of lime- 

 stone, which then, as now, were the dens of wild beasts ; and that 

 the caves and their contents of all periods older than the Pleistocene 

 had been destroyed. The solitary exception to this generalization 

 is the Pliocene cave at Doveholes, which was far enough from the 

 surface to escape the common destruction. It is possible to ascertain 

 in this case the minimum amount of denudation of the limestone, since 

 the stream introduced the clay, loam, and pebbles from the slopes 

 of the hills of Yoredale Shale, etc. and Millstone Grits to the west. 

 Under the existing conditions no water is delivered into the area of 

 the Victory Quarry from the west. Had there been drainage in 

 this direction, it would have disappeared in the limestone before it 

 reached the quarry. At the time when the cave was filled, it 

 obviously received the drainage of the rocks which now form the hills, 

 and must therefore have been at the bottom of a valley, instead of 

 being on a water-parting. I have attempted to restore this ancient 

 land-surface in the dotted lines of fig. 2 (p. 108), in which I have 

 carried the lower boundary of the Yoredale rocks along the plane of 

 dip to a sufficient height to command the cave. If this be taken as 

 an approximation to the truth, it will involve the lowering of the 

 general surface of the limestone by denudation to the extent of at least 

 330 feet, since the time when the cave was filled with its present 

 contents. From the wide range of swallow-holes over the plateau 

 of limestone, in places where streams would be impossible under 

 existing conditions, it may be inferred that the denudation affected 

 fche whole surface of this district. It would be sufficient to destroy 

 the ravine formed by the stream above the bone-cave at Doveholes, 

 and all the caves accessible to the Upper Pliocene mammalia, both 

 in this district and elsewhere. 



VIII. The Geography of Britain in the Upper Pliocene Age. 



We must now consider the geography of Britain during the Upper 

 Pliocene Age. The map published in ' Early Man in Britain ' in 

 1880 (p. 73) has been but slightly modified by later discoveries. 

 Mr. Jamieson 1 pointed out in 1882 that the Marine Crag of Aberdeen 

 is merely a remanie deposit, derived from the Bed Crag, and of 

 Pliocene age, and that, consequently, there is no evidence that the 

 Upper Pliocene coast-line touched any part of Scotland. Mr. Clement 

 Beid, 2 in his admirable work already cited, has collected together 

 evidence to show that the Lower Pliocene sea extended southward, so 



1 Quart. Journ. Geol. Soc. vol. xxxviii, p. 145. 



2 'Pliooene Deposits of Britain ' Mem. Geol. Surv. (1890) map, pi. i. 



