of Valleys aad Lakes. 309 



that (as I attempted to prove in my original memoir) the Alpine 

 and other ice-worn lakes known to me do not lie in areas of 

 special subsidence, nor in gaping fractures, nor in simple synclinal 

 basins, nor in hollows of watery erosion. If any one who reads 

 this is curious about them, he must refer to that memoir* ; but 

 this at least I may be permitted to say : I used at all events 

 arguments, even somewhat elaborate, and not mere statements, 

 and whether these arguments are fated to be successful time 

 alone will show. That they were at all events of some value, the 

 names of the distinguished geologists who have accepted my 

 theory helps to show ; and 1 could add to these other names as 

 high as the very highest of those on whose authority Sir Roderick 

 so much depends, did propriety permit me to quote from letters 

 and commit men to opinions which they have not expressed in 

 print. 



But before leaving the subject, let me say a little more about 

 the possibility of these lakes lying in fractures. For this pur- 

 pose let us take some of those that lie on the north side of the 

 Alps, partly in the region of the Miocene strata. If they lie in 

 lines of gaping fracture, nearly as wide as the present lakes, 

 then on the hills, say between the Lake of Lucerne and Thun, 

 and between Thun and the Lake of Zurich, the Miocene strata 

 would be crumpled up in zigzag lines across the average line of 

 strike, to an amount corresponding to the distance between the 

 severed strata in the spaces now overlooking and occupied by the 

 lakes. This is not the case. Again, if the fractures were mere 

 narrow cracks, then the amount of denudation that took place 

 so as to form the wide valleys has been enormous, and within a 

 mere fraction of what I require, especially when we consider 

 that the great denudation necessary to widen the fractures would 

 have filled up the lake-basins. The theory of the chief forma- 

 tion of Alpine valleys having been effected by weather, water, 

 and ice, would therefore still hold good. 



I might continue these arguments, and discuss in detail what 

 Sir Roderick has said about Scandinavia, North America, and 

 other regions, and among other things show how unprecise is 

 the knowledge that we actually possess respecting the details of 

 the boulder-beds that overspread some of them, and how unsafe 

 it is to conclude, because a country is not actually mountainous, 

 and does not now lie high above the sea-level, that it was never 

 covered by glacier-ice in motion, and may not at one time 

 have lain much higher. In spite of Agassiz's memoirs, it is not 

 long since all the lower Till of Scotland was considered not to 

 be ordinary moraine-matter at all, but to have been formed 



* They are also given in 'The Physical Geology and Geography of 

 Great Britain.' 



