DESCRIPTION OF SECTIONS. 257 



in the field to decide whether it is a lava or an intrusive sill (pages 

 76, 77). Microscopic examination reveals a structure which is not 

 consistent with that of a lava-flow, But the age of these sills remains 

 doubtful, and the extreme disturbance which prevails in the present 

 instance does not help towards a solution of the problem. 



Saindak* 



If now we proceed to the north-eastern margin of the range 

 bordering on the desert that surrounds the Gaud-i-Zirreh depres- 

 sion, we find that the rocks again dip inwards, therefore in this case 

 south-west. The section (Fig. 17) runs a short distance north- 

 west of the mountain called Saindak Koh. At the extreme margin 

 of the mountainous district are some Siwalik strata (a) much con- 

 cealed by the talus derived from the tall ranges of older rocks. 

 These tall ranges consist of tuffs and ash-beds (3); as in many other 

 localities they are cut through by basaltic dykes of a much later 

 date, while there occur also fissures which have afforded a passage 

 to mineral vapours that have decomposed the rock into brilliantly 

 coloured ochres. These tuffs and ash-beds belong to the flysch 

 system, they have a south-west underlie and are overlaid by volcanic 

 conglomerates containing boulders of such a large size that they must 

 indicate the proximity of an ancient volcanic centre. 



The uppermost beds of this conglomerate are overlaid by some 

 strata of coarse calcareous volcanic breccias of a bright red colour. 

 Then after a few feet of green shales, the next overlying rock is 

 nummulitic limestone (d) in which we find nummulites side by side 

 with volcanic pebbles. This point occurs a short distance north 

 of the Saindak spring which is situated in the middle of a syncline 

 of tertiary rock. These tertiary rocks consist of shales, sandstones 

 and limestones and all the fossils, even those from the strata resting 

 immediately upon the volcanic agglomerates are typical . Khirthar 

 forms. As the contact appears perfectly conformable, this is an 

 indication that in some localities the volcanic eruptions of the flysch 

 system continued up to a late horizon of the eocene. 



South of the Saindak spring, the tertiary strata dip north-east, 

 forming the south-western branch of the syncline. A thick-bedded 



( 79 ) 



