president's address. 



only a narrow neck would be left between them, which would be ulti- 

 mately cut down into a gap or ' col. ' Thus a region of deep valleys with 

 precipitous sides and heads, of sharp ridges, and of more or less isolated 

 peaks is substituted for a rather monotonous, if lofty, highland. 



The hypothesis is ingenious, but some students of Alpine scenery 

 think more proof desirable before they can accept it as an axiom. For 

 instance, continuous observations are necessary to justify the assump 

 tion of diurnal variations of temperature sufficient to produce any 

 sensible effect on rock at the bottom of a narrow chasm nearly fifty 

 yards deep and almost enclosed by ice. Here the conditions would 

 more probably resemble those in a glacidre, or natural ice cave. In 

 one of these, during the summer, curtains and festoons of ice depend 

 from the walls ; from them and from the roof water drips slowly, to be 

 frozen into stalagmitic mounds on the floor, which is itself sometimes 

 a thick bed of ice. On this the quantity of fallen rock debris is not 

 greater than is usual in a cave, nor are the walls notably shattered, 

 even though a gap some four yards deep may separate them from the ice. 

 The floors of cirques, from which the n6v& has vanished, cannot as a 

 rule be examined, because they are masked by debris which is brought 

 down by the numerous cascades, little and big, which seam their walls; 

 but glimpses of them may sometimes be obtained in the smaller corries 

 (which would be cirques if they could), and these show no signs of 

 either ' sapping ' or ' plucking,' but some little of abrasion by moving 

 ice. Cirques and corries also not infrequently occur on the sides as 

 well as at the heads of valleys; such, for instance, as the two in the 

 massif of the Uri Eothstock on the way to the Surenen Pass and the 

 Fer a Cheval above Sixt. The Lago di Eitom lies between the mouth 

 of a hanging valley and a well-defined step, and just above that is the 

 Lago di Cadagno in a large steep-walled corrie, which opens laterally 

 into the Val Piora, as that of the Lago di Tremorgio does into the 

 southern side of the Val Bedretto. Cirques may also be found where 

 glaciers have had a comparatively brief existence, as the Creux des 

 Vents on the Jura; or have never been formed, as on the slopes 

 of Salina, one of the Lipari Islands, or in the limestone desert of 

 Lower Egypt. 1 I have seen a miniature stepped valley carved by a 

 rainstorm on a slope of Hampstead Heath; a cirque, about a yard 

 in height and breadth, similarly excavated in the vertical wall of 

 a gravel pit; and a corrie, measured by feet instead of furlongs, 

 at the foot of one of the Binns near Burntisland, or, on a much 

 reduced scale, in a bank of earth. On all these the same agent, 

 plunging water, has left its marks — runlets of rain for the smaller, 

 streams for the larger; convergent at first, perhaps, by accident, 



1 A. J. Jukes-Browne, Geol. Mag., 1877, p. 477. 



