574 Notes on Geology and Mineralogy of Affghanistan. 



are of coarser texture, and composed of larger concretions.* 

 These specimens, although not found in situ, are when cou- 

 pled with the fore-mentioned rocks, sufficiently indicative of 

 the occurrence of the oolite system in the vicinity of the 

 defile, and the fragments obtained were no doubt brought 

 down through some of the lateral glens by the waters which 

 occasionally drain through them. 



Lower down we perceive on one side of the Pass, the 

 alternating strata of coloured clays and shales of the coal 

 formation, and on the other thick beds of nummulite lime- 

 stone belonging to the cretaceous system, the strata on both 

 sides having the same north-easterly dip. Still farther 

 down towards Dadur, the nummulite disappears beneath 

 thick overlying beds of sandstone and conglomerate ; the 

 pebbles imbedded in the latter rocks being of quartz, indu- 

 rated sandstone containing marine shells, and limestone con- 

 taining coralloids and shells. 



The conglomerate now prevails down to the mouth of the 

 Pass, and continues to form undulating and broken ground 

 even to Dadur, from whence on the desert side it disappears 

 beneath alluvial soils. The conglomerate is also found 

 opposite to the strata of shales near Sir-i-Bolan, where in 

 fact it forms one side of the Pass, and runs conformably with 

 the secondary strata. The sandstone appears to be in all 

 respects identical with that of the Siwalik hills in Upper 

 India ; and this circumstance, coupled with the discovery of 

 specimens of shells of the genera Planorbis, Melania, Cy- 

 rena and Unis, must stamp these rocks as belonging to the 

 tertiary formation. 



It would thus appear, that the mountains separating Cutchi 

 and Scinde from Afghanistan, are composed of the usual 



* The specimens of rocks and minerals, herein mentioned, being probably the 

 only collection brought from Affghanistan, are destined for the Geological Society 

 of London. 



