128 DONKIA PASS. Chap. XXII. 



looks as if diminished by being surveyed through the wrong 

 end of a telescope. 



A few rude cairns were erected on the crest of the pass, 

 covered with wands, red banners, and votive offerings of 

 rags. I found a fine slab of slate, inscribed with the 

 Tibetan characters, u Om Mani Padmi hom," which Meepo 

 allowed me to take away, as the reward of my exertions. 

 The ridge is wholly formed of angular blocks of white 

 gneissy granite, split by frost.* There was no snow on the 

 pass itself, but deep drifts and glaciers descended in hollows 

 on the north side, to 17,000 feet. The rounded northern 

 red shoulder of Kinchinjhow by Cholamoo lake, apparently 

 19,000 feet high, was quite bare, and, as I have said, 1 

 ascended Donkia to upwards of 19,000 feet before I found 

 the rocks crusted with ice,f and the ground wholly frozen. 

 I assume, therefore, that 19,000 feet at this spot is not 

 below the mean level at which all the snow melts that falls 

 on a fair exposure to the south : this probably coincides 

 with a mean temperature of 20°. Forty miles farther 

 north (in Tibet) the same line is probably at 20,000 feet; 

 for there much less snow falls, and much more melts in 

 proportion.! From the elevation of about 19,300 feet, 



* It was not a proper granite, but a highly metamorphic felspathic gneiss, with 

 very little mica ; being, I suspect, a gneiss which by metamorphic action was 

 almost remolten into granite : the lamination was obscure, and marked by faint 

 undulating lines of mica; it cleaves at all angles, but most generally along 

 fissures with highly polished undulated black surfaces. The strike of the same 

 rock near at hand was north-west, and dip north-east, at various angles. 



t Snow, transformed into ice throughout its whole mass : in short, glacial ice 

 in all physical characters. 



X Two secondary considerations materially affecting the melting of snow, and 

 hence exerting a material influence on the elevation of the snow-line, appear to 

 me never to have been sufficiently dwelt upon. Both, however, bear directly upon 

 the great elevation of the snow-line in Tibet. From the imperfect transmission of 

 the heating rays of the sun through films of water, which transmit perfectly the 

 luminous rays, it follows that the direct effects of the rays, in clear sunshine, are very 

 different at equal elevations of the moist outer and dry inner Himalaya. Secondly, 



