also steep walls and are deeply cut into the face of the cliff; nor have they any vegetation except at their lower ends. The spur that shuts in the glen on the left*, although just as energetically sculptured, is lower, has more rounded outlines, and is littered with detritus. It is also pierced by a larger number of side-glens, of which some, e. g. Chaltaning-saji, are pretty big. The principal glen ascends with a very gradual but regular slope. Seen in profile, the bottom of the glen makes a straight line with slight indentations, these being caused by the little brook which threads its way down it, generally divided into several rivulets winding amongst the gravel. Here and there small patches of vegetation, kamisch and tamarisks, dot the glen like islands; though generally the bushes and reeds keep to the sides, where they form »braidings» of varying breadth, often not more than two or three meters. Scarce anywhere is there at the foot of the cliffs a scree of detritus; the products of disintegration are evidently washed away by the successive floods that course down the glen and distribute the material evenly over its floor. A glen of
this type of structure can only occur in a region where the erosion is not constant. Did the brook flow for the greater part of the year it would give rise, on the one side of the glen or the other, to a deep and unchangeable channel at the foot of the cliffs, with the gravel-and-shingle terrace for one of its containing banks. Here however the erosive power of the brook is slight, at any rate infinitesimal as compared with the effect produced by the flood from a chance shower of rain. A flood of this kind, often a veritable torrent, fills the glen from side to side, and causes a complete rearrangement of the disintegrated detritus, filling up the channel of the constant spring-brook, so that it quite disappears and has to furrow out for itself a fresh path, which again is swept away by the next succeeding rain-torrent.
On the left, that is the southern, side of the glen the black schist was predominant all day; it lay at different angles, but as a rule was tilted up into an almost vertical position. At first it lay 78° towards the S. 1o° W., 72° towards the N. 8o° W., 8o° towards the S. 22° E., and 87° towards the N. 3o° W., all in the vicinity of Chaltaning-saji. At the point where the last observation was taken, a black schist cropped out also on the right side of the glen, though the rest of the
* In speaking of the right and the left sides of a glen, I always suppose myself to be standing with my back towards the head or upper end of the glen and my face towards its lower end. 'Thus the right or the left side is always consistently the same, equally whether I am travelling up or down the glen.
IIIFカラー高解像度
