358 LIEUT.-GEN. C. A. MCMAHON ON [May 10,00* 



quartz (by no means the most abundant material), fragments of 

 plagioclase-crystals, felstones, rhyolitic lavas, quartz-porphyries, 

 and other acid rocks, as well as magnetite and splintery fragments 

 of calcite. The fragments in this rock are angular to subangular r 

 some being plainly splinters with sharp points and edges. 



The Baltit Hornblende-Granite succeeds the ash-like rock. 



My next specimen is a red sandstone from a cliff at Yasin, 

 The grains are for the most part subangular : none are waterworn. 

 They consist of quartz, siliceous rocks, and grains of magnetite, but 

 none are recognizable as igneous rocks. The specimen is very much 

 stained with ferric oxide. 



At the mouth of the Tui River a quartzite weathering reddish 

 and a slaty-looking sandstone occur in alternate layers a 

 few feet thick. They have both suffered from pressure and from meta- 

 morphism. The quartzite is a peculiar rock : some of the quartz- 

 grains have a micro-tessellated structure, and the larger grains 

 exhibit undulose extinction. Some of them are fragments of 

 plagioclase, others are microcline. Possibly this rock may represent 

 the siliceous apophyses of a granite greatly crushed. 



At Barkulti, 15 miles south of Darband, Capt. Roberts discovered 

 a bluish-grey limestone more like the Gujhal Limestone than the 

 Nilt-Hini marbles or the stinkstones. It has a thickness of about 

 h mile. 



At Darkot a compact grey limestone comes in, which both my 

 son and Capt. Roberts identify as the grey limestone of Gujhal. 

 One of these specimens contains 64*40 per cent, of calcium car- 

 bonate and 34-07 of magnesium carbonate, but the other yields 

 63-88 per cent, of siliceous matter and only 32-47 of calcium car- 

 bonate, showing how greatly the beds contained in these limestones 

 vary in chemical composition. 



The Hatu Pir Granite comes in above the Darkot Limestone, 

 It does not exhibit parallelism of structure, but it has suffered con- 

 siderably from pressure. A sandstone also occurs above the Darband 

 Limestone. 



The succession from the Gujhal Grey Limestone up to the top of 

 the water-parting which separates the Pamirs from the Gilgit area 

 is thus the same both in the Darkot-Pass and Kilik-Pass sections. 

 The compact and comparatively unaltered limestones are succeeded 

 by sandstones and grits of apparently younger age. In both cases- 

 granite is an intruder in them, being, in the case of Kilik, the 

 Baltit Hornblende- Granite, and in the case of Darkot the Hatu Pir 

 Granite. 



(7) The Ashkurman (Ishkumman) Valley. 



Capt. Roberts very kindly undertook the exploration of this 

 valley, which runs northward to the Pamir, halfway between the 

 Yasin-Darband and Gilgit-Kilik valleys, for the purposes of the 

 present paper. 



The succession of rocks in this valley, commencing at its mouth 

 and proceeding northward, is as follows : — 



