GEOLOGrCAL DIVISIONS. IOJ 



These cases where the age of the volcanic rocks could be deter- 

 mined with a certain degree of accuracy are unfortunately few 

 compared with those in which no such clue could be discovered : 

 yet they tend generally to show that it is in the upper cretaceous that 

 the eruptions were most abundant, which frames in with the views 

 expressed by Mr. Griesbach as to their being contemporaneous with 

 the great basaltic outflows of the " Deccan trap. - " 



(b) Non-volcanic Rocks, 



The most conspicuous amongst the non-volcanic marine strata are 

 the shales and limestones ; the greatest bulk being constituted by 

 shales; while the limestones attract the attention by the manner in 

 which they rise into ridges. In certain regions a more arenaceous 

 facies sets in, the shales being interstratified with sandstones usually 

 highly calcareous ; in a few cases there occur conglomerates of small 

 rolled pebbles. As the fragments constituting the sandstones and 

 conglomerates often consist largely of the products of contempo- 

 raneous eruptions, the classification of the sediments as volcanic and 

 non-volcanic cannot always be very strictly adhered to. 



Just as the volcanic strata with which they are associated, these 

 rocks occur both in a comparatively undisturbed condition, and in 

 regions where folding is displayed to a considerable degree, and 

 their appearance differs accordingly. 



The shales here more argillaceous, here more arenaceous, very 

 commonly occur in thinly stratified masses with narrow beds of 

 limestone one foot or two feet thick at intervals. Such is their 

 appearance at K6h-i*Malik-Sidh where they are of a dull grey colour, 

 and again at Saindak where, in addition to grey, they exhibit many 

 shades of red and yellow. A very common variety is a splintery green- 

 coloured argillaceous rock, no doubt the analogue of the " olive shales " 

 described in other portions of Baluchistan and in Sind. In many 

 places, where associated with volcanic rocks, the shales are highly 

 calcareous and occur as flags often brilliantly coloured as is exhibited 

 C2 ( 19 ) 



