VREDENBURG: SKETCH OF BAL6CHISTAN DESERT. 



about twenty miles long and its maximum width is about five miles. 

 But many smaller dykes of similar composition occur to the north and 

 south-west, The main mass of the intrusion consists of granite, the 

 surrounding dykes of quartz-porphyries and quartz-felsites. The peaks 

 called Koh-i-Khwcija-i-Misk, K6h-i-Bibi-Mah, K6h-i-Borghar, Koh- 

 i-Hanjirdcin, all belong to the main granitic outcrop; in the plains 

 and valleys that separate them from one another the granite 

 has weathered into very typical "tors". South-east of K6h-i- 

 Khwaja-i-Misk there are some dykes of diorite-porphyry. 



The tertiary slates throughout the neighbouring districts exhibit 

 a very extreme type of regional metamorphism. Cleavage is most 

 perfectly developed, and they are altered into a very fine silky 

 micaceous material which produces a dazzling reflection in the sun- 

 shine (see PI. XIII). At their junction with the granite the effects of 

 contact metamorphism are added to those of regional metamorphism, 

 and the strata become so much indurated that they resist desintegra- 

 tion almost as well as the granite itself. In this way they rise to a 

 great height along the slopes of the Hanari Range, a line of granitic 

 peaks forming the south-eastern continuation of K6h-i-Bibi-Mah. 

 White mica, biotite, and garnet are amongst the most conspicuous of 

 the minerals developed by this contact metamorphism. The altered 

 rock is usually dark coloured, but where the slates have only been 

 affected by regional metamorphism they often exhibit brilliant green 

 and red hues in addition to their usual buff colour. Many of the 

 limestone bands still contain recognizable nummulites, which shows 

 that all these intensely metamorphosed rocks are tertiary. 



Quartz veins of large dimensions occur frequently both in the 

 granite and in the tertiary slates. 



From Ladis to the K6h-i-Tafddn. 

 South-east of Deri-Giaban the ranges of tertiary slates continue 

 unaltered in their characteristics up to Ladis, a locality situated on 

 the south-western border of the Mirjawa plain. The Ladis river 

 derives a perennial supply of water from the snows of the 

 K6h-i-Tafda*n, which permits a certain amount of cultivation in the 

 ( 90 ) 



