GEOLOGY. 247 



buted the similar phenomena presented by the mountains 

 and rocks in Finland to which reference has been made. 



With ice as with water, notwithstanding its hardness 

 and its tenacity, it seeks the lowest level to which it can 

 attain, and the glacier is ever in a state of flux from the 

 land towards the lower level of the sea, and on its 

 advance grinding away, smoothing, and striating the 

 surface of the rocks, past which, or over which, it flows. 

 The pressure, and consequent abrading power of a glacier 

 must be tremendous. The vis a tergo being such that it 

 treats as mere peebles in its path ridges, and even hills of 

 considerable elevation, and seems to pass as easily over 

 them as a deep river flows over the stones that may be in 

 its channel. 



And thus may be accounted for the numerous lakes 

 existing in the land, giving to its character and poetic 

 designation, and the existence of the lakes so abounding 

 in Norway and in Sweden. 



In the Quarterly Journal of the Geological Society, vol. 

 xviii., p. 185, in a paper by Professor (now Sir Andrew) 

 Ramsay, entitled ' The Physical Geology and Geography of 

 Great Britain/ may be found the first, suggestion, and illus- 

 tration, and proof of this fact. There ' he has shown that 

 the innumerable rock-enclosed basins of the Northern 

 hemisphere do not lie in gaping fissures, produced by 

 underground disturbance, nor in areas of special subsid- 

 ence, nor in synclinal folds of the strata, but that they are 

 true hollows of erosion.' 



1 cite the statement of Professor Geikie, in his ' Scenery 

 of Scotland, viewed in connection with its Physical Geo- 

 graphy ;' and to this work I am indebted for the following 

 illustrations : 



' Lakes, at least those which mottle the surface of Scot- 

 land, may be grouped into three classes: 1st, those which 

 lie in original hollows of the superficial drifts ; 2d, those 

 which have been formed by a bar of drift across a valley 

 or depression ; 3d, those which lie in a basin-shaped cavity 

 of solid rock.' 



