1866.] the Western Himalaya and Afghan Mountains. 119 



irregularly in the rock, or as smaller geodes mixed among long cylindrical and 

 twisted branches of quaz-tz running through the mass. (See figs. 1, la. plat. X.) 

 I must confess, I had some difficulty in understanding these branches ; they look 

 precisely like the ai-ms of a canal or like small rhizomes, and they sometimes 

 have the form of worm-burrows ; they begin with thick branches or trunks about 

 the size of the finger and throw out smaller twigs ; they are often 6 or 8 inches 

 long, and are cut obliquely by both stratification and cleavage. I have come to 

 the conclusion, after examining a great many of these cylinders, that they are 

 gas-vents, similar to the amygdala in origin, the imprisoned gas, in its efforts 

 torraohthe surface, having had sufficient strength to force a long passage 

 though the viscid paste.* Dip 55° to 60° about 600 ft. 



5. Amygdaloidal greenstone, graduating to trachyte ; with innumerable 

 small geodes, rounded and pressed together. The greenstone becomes rough 

 and gritty and passes into a trachyte, it is much less amygdaloidal ; and on 

 the other hand, where the rock is excessively amygdaloidal, the paste is a 

 dark brownish black rock, which is cleaved into, well defined slabs, and breaks 

 easily into prismatic fragments. This bed forms a depression between harder 

 layers. The stratification is easily seen by the several courses of the rock 

 superposed one on the other ; but of course it is not seen in the thickness of 

 each course about 200 ft. 



6. Pale bluish greenstone, hard, compact, with conchoidal fracture ; it is 

 closely spotted with irregular dots of hornblende. At the base of each compact 

 layer, there is a margin 1 or 1£ foot thick and very amygdaloidal, the 

 geodes being filled with quartz. It is a very hard stratum ... about 150 ft. 



7. Closely set amygdaloid. The paste is a greenish felspar, sometimes 

 very 'compact and then dark, and cleaved into slabs half an inch thick . 

 sometimes light in shade and with the amygdala rather irregular and nearly 

 touching one another. In many specimens, the felspathic paste shows 

 a division of the felspar into a bluish or greenish mass and patches of white 

 felspar ; but there is no crystallization. Dip 70° nearly due E. The fels- 

 pathic paste decays pretty quickly and thus this bed forms a depression 

 on the hill sid.e 50 ft. 



8. This is the stratum on which the celebrated Buddhist ruin is built ; it 

 is the highest summit of the Tukt-i-Suliman (6263 ft.) It is composed 

 of very hard, dark greenstone, with amygdala of white quartz, occurring 

 sparingly. Beds of lighter coloured greenstone, with specks and nodules of 

 augite are interstratified. A great many well defined long cylinders of quartz, 

 either white or black or smoky, such as I have described as gas vents, are 

 seen here. This stratum is a hard saddle or ridge ; nearly vertical, and 

 dipping easterly 60 ft. 



* I have since read that Dr. MacCulloch observed in Little Cambay, one 

 of the Western Islands of Scotland, amygdaloid containing elongated cavities 

 similar, I believe, to those which are here described. 



