1867.] the Western Himalaya and Afghan Mountains. 47 



of the efflorescence which accompanies the borax at Pnga. From 

 the extensive beds of gypsum and impure salt found in Rukshu, little 

 doubt can be entertained that the saliferian is there well developed, 

 and by analogy it is to be presumed that the same formation is 

 also to be seen in Rodok. Borax is said to be exported from Rodok 

 in large clean crystals, but I do not know whence they are obtained ; 

 that it does come from Rodok appears however pretty certain ; and 

 that is another resemblance with Rukshu, and another reason for 

 believing that the saliferian is probably well developed in Rodok, and 

 is there accompanied by hot springs and fumaroles exhaling boracic 

 acid. 



I have never seen any fossil which had been brought from Rodok, 

 Shayokh or Nuba ; it is impossible therefore to say to what age 

 belong the beds of limestone mentioned by Dr. Thomson. The beds 

 are called " primitive limestone ;" but as Jacquemont, Vigne, Thom- 

 son and others speak sometimes of fossiliferous limestone (such as the 

 Manus Bal limestone in Kashmir) as " primitive," it is difficult to 

 know for certain what is meant by that somewhat antiquated term. 



79. The Korakoram Chain is a range of very great extent, begin- 

 ning at the Pamer Steppes and reaching to the S. E. as far as the 

 centre of Thibet in longitude E. 94° and as low as latitude N. 30°. 

 The plateau near its south-western slope is from 15,000 to 17,000 feet 

 high, and is an arid tract of horizontal alluvian covered with loose 

 stones and supporting very little vegetation ; more to the north it is 

 a labyrinth of wild valleys. Near the Mashabroom mountain (above 

 26,000 feet) the soil of the valleys between the spurs is to a great 

 extent covered by glaciers ; where not so covered, it is often an 

 indurated clay strewed with debris of pale limestone a good deal 

 worn and weathered, and with globular cystidese in very great 

 abundance. Mr. Ryall, of the Great Trigonometrical Survey, gave 

 me one of the pieces of limestone and some of the fossils. The lime- 

 stone is an argillaceous dolomitic limestone, pale yellowish brown, with 

 a few patches pale blue, weathering like frosted glass, and resembling 

 a good deal of the rocks of the Weean and Kothair groups of 

 carboniferous limestone. The sphctronites, however, point to a silurian 

 epoch, these echinoderms having not been found as yet in formations 

 posterior to the Wenlock limestone. 



