Vol. 58.] GLACIER-LAKES IN THE CLEVELAND HILLS. 571 
and during nearly the whole of that time had paid special attention 
to its Glacial geology ; but very many of the problems which pre- 
sented themselves were insoluble, until the Author came down and 
threw a flood of light upon them. He regarded the reading of this 
paper as marking an extremely important advance in our knowledge 
of Glacial geology. 
The AvrHor thanked the speakers for the terms in which they 
had spoken of his communication ; he was particularly glad to have 
the general approval of Mr. Reid and Mr. Barrow for the views. 
contained in it. With the latter he most fully agreed, as he had 
himself worked upon the Glacial phenomena of the district for many 
years without obtaining any enlightenment, before he discovered the 
clue to their interpretation. 
In reply to Mr. Salter, he said that he had exercised the utmost 
caution in dealing with dry ravines in limestone-rocks, and admitted 
their glacial origin only in the most patent cases: very few were 
mentioned in the paper. He dissented entirely from the view that 
the gorges which he had described were due, as suggested, to 
protracted denudation of limestone-rocks: they bore every indication 
of extremely rapid denudation. 
He wished strongly to emphasize his indebtedness to the admir- 
able Drift-mapping of the Geological Survey, which had been 
confirmed by his own investigations in a remarkable way. 
