MCMAHON : PETROLOG1CAL NOTES ON SOME PERIDOT1TES, ETC, 



So there can be but little doubt that we have here a true volcanic 

 series. 



I must not be PMsunderstood to deny the existence of intrusive 

 rocks. I have myself seen these some miles south of Karzok on the 

 Tso Morari and as far north as Shushal. Intrusive rocks doubtless 

 occur au: .g *he volcanics, indeed this is but what might be ex- 

 pected and may doubtless account for the ambiguity in the two 

 published descriptions. 



As to the lithology of the beds, beyond what is implied in 

 the above passages, nothing need be added to the descriptions of 

 Dr. Stoliczka, Mr. Lydekker, and later of Colonel McMahon." 



The microscopical examination of the following specimens col- 

 lected by Mr. R. D. Oldham are described in this paper, viz. :— 



No. 8 — 278. Lherzolite from the Priga valley, Ladakh. 

 „ 8 — 276. Serpentine after Troctolite, Pdga valley, Ladakh. 

 „ 8 — 279. Porphyritic diorite, from N. of Chang La, Ladakh. 

 „ 8—280. Porphyritic diorite. Junction of Chang and Inchine 



valleys, Ladakh. 

 „ 8—281. Porphyritic diorite. Junction of Chang and Inchine 



valleys, Ladakh. 

 „ 8 — 271. Volcanic ash, from the Puga valley, Ladakh. 

 „ 8^272. Volcanic ash, from do. do. 



„ 8—275. Volcanic ash, from do. do. 



The following specimens collected by Mr. T. D. La Touche are 

 also described :— 



No. 8 — 293. Serpentine from valley W. of Sirsa La, Zdnskar. 

 „ 8 — 294. Serpentine from do. do. 



The second edition of Medlicott and Blanford's Manual of the 

 Geology of India by Mr. R. D. Oldham contains at page 346 the 

 following reference to the Ladakh igneous and volcanic rocks :— 



l< In the sections eastwards of Leh, conglomerates are said to 

 occur near 'he upper limit of the series, and these conglomerates 

 contain pebbles of the volcanic beds, which will presently be 

 described, and of nummulitic limestone. The occurrence of these 

 last shows that the beds fiad locally been elevated and exposed to 

 ( 6 ) 



