IGNEOUS ROCKS. ri$ 



IV.— tIgneous Rocks. 



The almost entire absence of igneous rocks in situ is very striking. 



Absence of igneous No trace, even of pebbles, was to be seen either 

 rocks south of the Bara in the Khanki or Mastura Valleys or in the 

 ValIey# stream beds of Maidan and Waran. At Bagh 



however, I found, in a house, a polished pebble of olivine dolerite, 



Olivine dolerite from which had evidently been used for crushing salt. 



the Bara Valley. This pebble had no doubt been brought from 



the BaYa Valley, for on reaching Dwatowi I found numerous blocks 



and pebbles of the same rock lying in the bed of the Bdra river. 



Pebbles of it also occur on the hillsides among 



Not in situ. & 



the sub-recent conglomerates and gravel beds. 

 I could not, however, find the rock in situ> but it probably occurs at 

 the head of the valley, possibly along the fault separating the palaeo- 

 zoic and mesozoic rocks : yet in the lower reaches of the valley, where 

 the fault is seen, I found no signs of igneous intrusion. 



In the neighbourhood of Jamrud Fort and throughout the Khaibar, 



Dolerite of Ghund P eDD i es and blocks of gabbro and dolerite are 

 Ghar. very common, but the only locality, in which I 



found any of these rocks in situ, was on Ghund Ghar, the hill 

 already mentioned as overlooking, on the south, the entrance to the 

 Khaibar. On the north-east flank of this hill a small intrusive sheet 

 of dolerite is found among the shales, while higher up the hillside 

 are other intrusions, one about half-way up and another about 200 



Intruded among the feet below the summit. All these intrusions 



carboniferous limestones. are qu j te smal j . that nearest the summ j t occurs 



among the carboniferous limestones which it has locally altered into 

 a fine saccharoid marble. 



The rock is a green enstatite-dolerite, and under the micro- 

 scope shows a confused mass of crystals of 



Microscopic characters. . . , 



plagioclase, augite and enstatite with numerous 



secondary minerals, including chiefly green hornblende, bastite, 



I A ( US ) 



