450 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [May 28, 



space and close it up, so as to dam the drainage-waters and form a 

 lake: instances of this have been given by Major Godwin -Austen*; 

 I shall refer to the circumstances in the latter part of this paper. 

 Of another effect of the projection of fans into a narrow valley, I 

 will give an example here : — There is a pass leading out of Bupshu, 

 a district of Ladakh, called Folokonka ; this is something over sixteen 

 thousand feet above the sea : a long gradually sloping valley leads 

 up to it ; and a similar slope leads down on the other side. The 

 actual pass is made by a fan which comes from a ravine in the moun- 

 tains that bound the valley on the north ; the occurrence of that fan 

 must latterty have determined the position of the pass-summit ; and a 

 curious accompaniment of this circumstance is that the water flowing 

 from that ravine is divided, part flowing into one drainage-basin, and 

 part into the other. 



There is yet another form of fan to be noticed. Hitherto they have 

 been described as originating from one point, a gap or gorge in a line 

 of mouutain, and from there spreading out unbroken by other rocks ; 

 and this is truly the general form of them ; but it sometimes happens 

 that the form of the ground is different and produces effects less 

 simple. For instance, on the right bank of the Indus, at Leh itself 

 and many miles to the south-east, there is a succession of ravines 

 coming from a great granite-range on the north-east, and widening 

 as they come ; the spurs between them, instead of ending off suddenly 

 in a great slope, lessen in height and in width from far back, but 

 continue as jutting rocky spurs on to the river Indus, which itself 

 washes them. The side streams have carried the same sort of mate- 

 rial as in other cases. "Where the ravine begins to widen may be 

 counted the apex of the fan : from here the stream has at different 

 times spread and wandered ; and a form of surface partly resembling 

 the fans has been produced ; but the spurs of the hills have both 

 confined the stream and reflected it, so that the simple shape of the 

 low cone is not kept to. For example, the triangular space between 

 the town of Leh and the Indus-alluvium is filled with a deposit mo- 

 dified in its extension by the causes given above ; we will call it, for 

 distinction, a " confined fan." It is composed of sand, of granite- 

 stones (some angular, some half-rounded), and of larger blocks of 

 granite : these are a good deal mixed together ; but the whole is 

 stratified, with frequent false-bedding. The beds dip and the ground 

 slopes at an angle of 3°, generally to the S.S.W.,but with some lateral 

 variations. In this instance the descent from where the widening 

 began to the flat of the Indus is 1200 feet in 3| miles. 



We should now consider the relationship of the fans to the allu- 

 vium proper of the main valleys. 



If the level of this latter alluvium is remaining, on the whole, sta- 

 tionary (the main river neither deepening its bed nor raising it), and 

 if the fan is undergoing increase, then the fan-stuff will just extend 

 over the alluvium, gradually encroach on it in area; and, stratigra- 

 phically, rest upon it. But I think it is a more usual case that the 

 river-alluvium has been increasing contemporaneously with the 



* On the Pang Kong district of Ladakh, Journ. As. Soc. Beng. vol. xxxvii. 



