Septembee 9, 1910] 



SCIENCE 



327 



the glaciers of the Alps have now degen- 

 erated into senile impotence; but in valley 

 beds over which they passed when in the 

 full tide of their strength the flanks show 

 remnants of rocky ridges only partly 

 smoothed away, and rough rock exists on 

 the "lee-sides" of ice- worn mounds which 

 no imaginary plucking can explain. The 

 ice seems to have flowed over rather than to 

 have plunged into the obstacles in its path, 

 and even the huge steps of limestone ex- 

 posed by the last retreat of the Unter 

 Grindelwald Glacier have suffered little 

 more than a rounding off of their angles, 

 though that glacier must have passed over 

 them when in fullest development, for it 

 seems impossible to explain these by any 

 process of sapping. 



The comparatively level trough, which 

 so often forms the uppermost part of one 

 of the great passes across the watershed of 

 the Alps, can hardly be explained without 

 admitting that in each case the original 

 watershed has been destroyed by the more 

 rapid recession of the head of the southern 

 valley, and this work bears every sign of 

 having been accomplished in pre-glacial 

 times. Sapping and plucking must have 

 operated on a gigantic scale to separate the 

 Viso from the Cottian watershed, to isolate 

 the huge pyramid of the Matterhorn, with 

 its western spur, or to make, by the reces- 

 sion of the Val Macugnaga, that great gap 

 between the Strahlhorn and Monte Rosa. 

 Some sceptics even go so far as to doubt 

 whether the dominant forms of a non- 

 glaciated region differ very materially 

 from those of one which has been halfr 

 buried in snowfields and glaciers. To my 

 eyes, the general outlines of the mountains 

 about the Lake of Gennesaret and the 

 northern part of the Dead Sea recalled those 

 around the Lake of Annecy and on the 

 southeastern shore of Leman. The sand- 

 stone crags, which rise here and there like 



ruined castles from the lower plateau of 

 the Saxon Switzerland, resembled in out- 

 lines, though on a smaller scale, some of the 

 dolomites in the southern Tyrol. The 

 Lofoten Islands illustrate a half-drowned 

 mountain range from which the glaciers 

 have disappeared. Those were born among 

 splintered peaks and ridges, which, though 

 less lofty, rival in form the Aiguilles of 

 Chamonix, and the valleys become more 

 and more iceworn as they descend, till the 

 coast is fringed with skerries every one of 

 which is a roche moutonnee. The neve 

 in each of these valleys has been compara- 

 tively ineffective; the ice has gathered 

 strength with the growth of the glacier. 

 As can be seen from photographs, the 

 scenery of the heart of the Caucasus or of 

 the Himalayas differs in scale rather than 

 in kind from that of the Alps. Thus the 

 amount of abrasion varies, other things 

 being equal, with the latitude. The grind- 

 ing away of ridges and spurs, the smooth- 

 ing of the walls of troughs,^^ is greater in 

 Norway than in the Alps ; it is still greater 

 in Greenland than in Norway, and it is 

 greatest of all in the Antarctic, according 

 to the reports of the expeditions led by 

 Scott and Shackleton. But even in Polar 

 regions, under the most favorable condi- 

 tions, the dominant outlines of the moun- 

 tains, as shown in the numerous photo- 

 graphs taken by both parties, and in Dr. 

 "Wilson's admirable drawings, differ in de- 

 gree rather than in kind from those of mid- 

 European ranges. It has been asserted 

 that the parallel sides of the larger Alpine 

 valleys — such as the Rhone above Mar- 

 tigny, the Liitschine near Lauterbrunnen, 

 and the Val Bedretto below Airolo — prove 

 that they have been made by the ice-plough 

 rather than by running water; but in the 



" If one may judge from photographs, the 

 smoothing of the flanks of a valley is unusually 

 conspicuous in Milton Sound, New Zealand. 



