676 Notes on the Geology of the Punjab Salt Range. [No. 7. 



the surface. This appearance however should not be confounded 

 with a somewhat similar one also seen in the same beds, and pro- 

 duced by the decomposition of pyrites in the sandstone itself. 



I shall now describe an actual trap, which, though far from com- 

 mon, is interesting as a bona fide representative of its class. This 

 trap occurs only at the east end of the range and is confined to the 

 red salt-marl, and appears in connection with one of the best marked 

 faults in the range (vide Choa valley section). It occurs in four 

 places, viz. : 1st, On the east side of the Kiura gorge about half a 

 mile above the village. 2nd, On the west shoulder of Mt. Karingli, 

 in a nulla opposite the small village of Chumbi. 3rd, On the N. W. 

 side of the Makraj gorge, above the waterfall. 4th, In the Nilawan 

 ravine below Nurpur, a short distance from the salt choki ; and at a 

 few other spots. The colour of this trap is a dull brownish or red- 

 dish purple. It is trachytic, and tolerably compact and hard, and is 

 traversed in every direction by short capillary markings (probably, 

 very minute crystals of tremolite), which in perfectly un weathered 

 specimens are occasionaly obsolete. 



Although from the nature of that rock, its junction with the red 

 marl is never well seen, yet its action on it is sufficiently well 

 marked. It converts the bright red marl into an orange or cream 

 coloured mass, very vesicular at the immediate point of contact,, 

 and containing kernels (as at Nurpur) of a greasy earth, like soap- 

 stone, at other places (Kiura) kernels of a glassy zeolite and geodes 

 with crystals of a similar mineral. The vesicles in the marl are 

 usually coated with an impalpable black, red, or yellow powder. 



The trap itself changes somewhat in character in contact with the 

 marl, becoming amygdaloidal and otherwise assimilating to that rock. 

 When decomposed, creamy yellow spots become developed in the 

 trap, which gradually enlarge, till the mass becomes converted into 

 a yellowish-white bole, or hard earth traversed in every direction by 

 radiating spiculae (tremolite ?) which seem to exist in a latent form 

 till rendered visible by decomposition. 



The gypsum in the vicinity of the trap is rendered coarsely gra- 

 nular and somewhat incoherent. So conclusive is this appearance 

 that it was one of the arguments on which Dr. Fleming based his 

 theory* of the eruptive origin of the red marl itself, gypseous 

 * Vide Quarterly Journal Geographical Society, for August, 1853. 





