Yol. 56.] THE RIVER-SYSTEM OF NORTH WALES. 231 



more so than if this practical question had been discussed by him. 

 The paper had, however, some bearing upon this subject. Although 

 the drainage-area is large, the rainfall heavy, and the rocks are 

 comparatively impervious, he had thought that there might be a 

 difficulty in raising the level of the water in the lake sufficiently to 

 afford the necessary legal compensation to the riparian rights below 

 it, because of the various possible outlets at a little higher level 

 than the existing one, the presence of which outlets the Author had 

 pointed out. The submergence of the town of Bala would perhaps 

 be a small matter, compared with the importance of the supply of 

 such pure water to London. There was one point which he should 

 like to see made clearer. He had visited Bala Lake in all states of 

 the weather, and he had noticed that a considerable area of land at 

 the northern end of the lake was soon under water when the rainfall 

 was heavy, from wdiich he inferred that the margin of the lake had 

 there a gentler slope than the Author's words would lead one to 

 surmise. 



Mr. Strahan observed that this paper dealt with two highly 

 speculative subjects. He understood the Author to state that the 

 lake was rock-bound in all directions except to the south-west, 

 where it was possibly dammed by Drift. If this Drift-dam were 

 due to earth-movements, those movements must be of post-Glacial 

 age. But movements of so late a date and on such a scale were 

 unknown in this country. The alluvial flat at the foot of the lake 

 which the Author had ascribed to the Dee was more probably the 

 alluvial fan of the Treweryn, a turbulent tributary scarcely less 

 important than the Dee itself. The Author had shown that there 

 was an intimate connexion between the faulting and the form of 

 the valley, but this might be attributed to the fact that the faults 

 threw in soft strata among hard volcanic rocks ; the Bala Fault was 

 believed to be of pre-Triassic age, and it was hardly likely that any 

 alteration of surface-level produced by it could have survived from 

 so early a period. The contention that portions of certain north- 

 and-south stream-courses formed relics of once continuous radiating 

 valleys was too great a demand upon his credulity. 



Though not accepting all the Author's conclusions, he congratulated 

 him upon a highly suggestive communication. 



Prof. Groom thought that the Author had made out a very strong 

 case for the original connexion between the different river-sections 

 radiating from the North Wales centre. With respect to the dis- 

 locations, both the Author and himself had often been struck with 

 the close connexion which existed between faults and valleys in 

 North Wales. The dominant movements along the north-east and 

 south-west lines appear to have occurred at a number of distinct 

 epochs in North Wales and the Border counties. Continental 

 geologists had almost invariably regarded the old Welsh Highlands 

 as a part of the Caledonian system, but there appeared to be little 

 doubt that the chief folding had taken place in Old Red Sandstone 

 times, as Ramsay had long ago maintained. Other movements in 

 the same sense had taken place towards the close of the Upper 



