356 LIEUT.-GEN. C. A. MCMAHON ON [May I9OO, 



from the precipitous craggy ranges and deep narrow valleys south of 

 them.' 



(6) Gilgit to Yasin and the Darkot Pass. 



Between Gilgit and Gupis the strike is hard to determine precisely, 

 as it is very wavy and the rocks are much jointed : it appears, 

 however, to be somewhat south of west. The dip varies from 60° 

 to 90°. 



Proceeding in a north-westerly direction from|Gilgit up the Yasin 

 River, the foliated diorite of Gilgit passes into a very fine-grained 

 schistose diorite which is well seen in a cliff at Hinzal, 10 miles 

 west of Gilgit. It is a dark-grey compact rock and very fine-grained 

 under the microscope. It is composed of hornblende, biotite, and 

 magnetite. The groundmass consists of granular water-clear 

 felspar. 1 I think that it is only a variety of the Gilgit diorite. 



At the 12th milestone west of Gilgit a bed of white crystalline 

 limestone, 30 feet thick, striking east and west and dipping 80° 

 northward, crops up. This is evidently the continuation of the bed 

 between Gilgit and Nomal already described (p. 349). It is nearly due 

 west, and on the exact line of strike, of the Gilgit-JNomal outcrop. 



The Baltit Hornblende-Granite comes in again at Bagu, 

 18 miles from Gilgit. Capt. Roberts sent me three specimens from 

 a cliff opposite Bagu, and my son two from Bagu itself. 



From a cliff on the right bank of the river, opposite Sherkila, 

 23 miles west of Gilgit, I have five specimens of amphibolites 

 which may be shortly described as intensely altered diorite s. 

 They are composed of hornblende, felspar, epidote, biotite, apatite, 

 iron-ores, and a little calcite. Two of these specimens have passed 

 into the condition of microgranular schists, but in the others the 

 original structure of diorite can be made out. Phenocrysts of 

 hornblende are present in all, and in one of them porphyritic 

 plagioclase-felspars set in a felspathic groundmass can be seen. In 

 three specimens the felspar of the groundmass is orthoclase. The 

 hornblende has to a large extent been converted into granular 

 epidote and biotite, and the plagioclase-phenocrysts into matted 

 masses of silvery mica, epidote, and zoisite. The original zonal 

 structure can be traced in them, and in some the alteration is 

 confined to the more basic central zones. The least changed of 

 the hornblende-crystals are anything but fresh, and polarize feebly. 



An interesting complex of highly-altered rocks is found in a cliff 

 called Gaisheli, a few miles farther up the river, between Sherkila 

 and Gich. The first of these is an altered diorite, in which the 

 phenocrysts are oligoclase. They are not unfrequently broken, 

 showing that the rock has suffered from strain and pressure. 



Three of the specimens are epidotic hornblende-schists, 

 which do not differ essentially from the rocks associated with the 

 Sherkila altered diorites just described. Apatite is absent, however, 

 while quartz is added to the groundmass, and in two specimens 



1 When tested in converging polarized light the grains proved in every case 

 to be felspar, and not quartz. 



