C. E. Be Ranee — Qlaciation of N.W. of England. 417 



were deposited, the land must have been elevated to a level only 50 feet 

 lower than at present. But, unfortunately for that argument, the sands 

 at Blackpool, and all over the North-west of England, are overlaid 

 by marine Upper Boulder-clay, at all levels up to 800 or 1,000 feet 

 above the sea.^ If, therefore, his theory be true, the country must 

 have subsided a second time more than a 1,000 feet for the Upper 

 Boulder-clay to be deposited, which I at present see no grounds for 

 supposing. 



Mr. Mackintosh takes exception to the statement in my paper,^ on 

 the " Surface Geology of the Lake District," that 1st, those lakes 

 deliver as well as receive their waters, and 2nd, "that consider- 

 ing the immense depths of the lakes, the deep chasms in which 

 they lie, it is impossible to say that immense quantities of detritus do 

 not lie concealed beneath their placid waters," in opposition to those 

 that hold that the limited excavating power of the Lake-district rivers 

 " is proved by the small quantity of detritus they have yet been able 

 to deposit." He states that he " ascertained from various persons, 

 who were thoroughly acquainted with all the ins and outs of the 

 Lake, that none of the detritus, or sediment brought in by the Brathay 

 river, can find its way through the lake to the sea." But I am still 

 perfectly unconvinced of any error in my statements ; for (1) were 

 the " various persons " competent judges, and (2) admitting that 

 they were, the question to be decided is not " the ins and outs of the 

 lake," but of the quantity of matter held in chemical solution and 

 mechanical suspension, and pushed along at the bottom of the stream 

 at the point of outlet; (3) that sediment is brought into the lake, not 

 only by the Brathay, but by other streams, and by a portion of every 

 rain-shower that falls upon the surrounding hills ; that (4) granting 

 that a deep current moving to the north is generated by the S.W. 

 wind, this would aid the movement of sediment in all the lakes 

 north of the great watershed, including all the chief lakes of the 

 district, with the exception of Windermere and Coniston mere ; and 

 that (5) though in my paper in 1869,^ I took especial care to point out 

 the enormous lacustrine deposits, which no doubt exist at the bottom 

 of these lakes, I cannot admit, with him, that even in " Lahe 

 Districts," that " Lacustrine deposits, which have all resulted from 

 the action of fresh-water, afford the only true measure of sub-aerial 

 denudation since the Glacial period." 



In the first portion of his last paper Mr. Mackintosh states, in 

 regard to Wastdale Screes, that the "idea at first suggested itself 

 that a great stream of land-ice may once have tumbled over the 

 Screes escarpment, and smoothed the above rocks (between Green- 

 dale and Wastwater) in its passage across the dale. Mr. De Eance 

 has expressed a similar idea, but I do not think it can be reconciled 

 with attentive consideration of the physical geography of the 

 district." But unfortunately he omits to give the result of his own 

 considerations on the subject. In his section, however (Fig. 3), 

 through the roches moutonnees, west of the lake, he clearly shows 



1 Quart. Journ Geol. Soc. vol. xxvii., part i. 

 2 Geol. Mag., Vol. VI. 



TOL. Till, — NO. LXXXVII. 27 



