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GRIESBACH : GEOLOGY OF THE CENTRAL HIMALAYAS. 



Crystalline rocks. 



The lowest group in all the sections of the Painkanda area is 



formed by crystalline rocks, which build up 

 the mighty chain of hills which extend from the 

 Nanda Devi, Trisul and Dunagiri in a north-westerly direction, and 

 end in the noble cone of the snow-covered Kamet. These crystalline 

 rocks form as it were a wide arch or roof, with its apex greatly eroded 

 and worn away, now mostly buried under masses of snow and ice. 

 Huge glaciers fill the higher valleys in this range, and send down 

 enormous masses of debris, often choking the narrow gorges of the 

 main valleys into which they fall. One of the glaciers of this central 

 range is the Raikana, the foot of which forms the beginning of sec- 

 tion i of plate I. 



As already described in the chapter on the metamorphic series, it 



Schists Vaikritasys- w ^ ^e remembered that the upper beds of the 

 tem - crystalline series are schists. They are clearly 



of sedimentary origin, and pass upwards into the haimanta system • 

 but I have separated them under the name of the vaikrita system. 

 They are chiefly composed of mica-schists with talcose slates and 

 thinly stratified* gneiss. The latter shows the gradual passage from 

 gneiss into mica-schist markedly, the gneiss stratum usually forming 

 the centre bed of a group of schists, the outer strata of which are 

 mica-schists passing gradually through quartz rock with garnets into 

 a fine grained grey gneiss in which* garnet forms one of the accessory 

 minerals. The gneiss is often in thin flaggy beds, divided by a few 

 inches of mica-schist, which is replaced here and there by talcose 

 beds. An enormous thickness of metamorphic rocks is thus made 

 up of a repetition of more or less similar series of schists and 

 gneiss. 



Such is the vaikrita system which overlies the great mass of 



Overlies the gneiss of bedded gneiss which forms the main range of 

 the mam range. Garhwdl and which is lithologically and struc- 



turally the same as Stoliczka's ( Central gneiss ' of the north-western 

 Himalayas. 



( 90 ) 



