1838.] the Ghorba7id mines, and Hindu Kush. 52$ 



thering or been fractured by some external force, these were frequently 

 seen uninjured and protruding in rounded nodules beyond the general 

 surface. A similar fact, if I mistake not, has been noted by M. Brong- 

 niart as occurring in a granite of Corsica, and taken in connection with 

 Hall's experiments on the fusion and subsequent refrigeration of basalt, 

 it forms a most interesting link in the chain of evidence which goes to 

 connect granite with rocks of undoubted igneous origin. This same 

 peculiarity of mineralogical structure was again remarked by me when 

 I came on what I thence conclude to be part of the same outbreak of 

 granite (though at a somewhat diminished elevation), between Agrabad 

 and Saighan on the road north of Bdmian, and it, is not a little re- 

 markable that it was here accompanied by an almost basaltic arrange- 

 ment of the rock. This is so evident that Captain Burntes in his for* 

 mer journey, viewing it merely with the eye of a traveller says, " Cliffs 

 of granite blackened by the elements rose up in dusky but majestic 

 columns not unlike basalt." Next to the granite lies the great slate 

 formation I have mentioned, and which must be considered as including 

 gneiss, mica and clay-slate of numerous varieties, with chlorite and other 

 subordinate slates, as well as veins of carbonate of lime and quartz, the 

 latter sometimes attaining a thickness of two or three hundred yards, 

 though more frequently from a few inches to two or three or four feet* 

 Of all these the gneiss appears to occupy the inferior position though 

 this is by no means constant, on the contrary every possible alteration 

 may be found amongst them. The formation is of very great extent 

 reaching in length from Attok, where we first came on it, in the form 

 of black roofing slate, to the longitude of Bdmian, 100 miles west of 

 Kdbul. It probably extends much farther, but I speak only of what I 

 have seen, 



Its mean breadth may be safely stated at between twenty and thirty 

 miles, at least three perfect sections which I have made of it were all 

 fully of that extent. It runs in the first instance north of the basin of 

 Peshawar, hard, blue, non-fossiliferous limestone*, which we had 

 traced upon it from Hasan Abdul, parting from it at the Gidergalla, 

 and going round to form the southern edge. It is then continued 

 north of the basins of Jalalabad and Kabul, sending down the two 

 southerly deflexions or outlying ridges which mark their ancient mar- 

 gins, and which we traversed by the Khaibar pass, and that which leads 

 through Tiyen to Balkh, distances of thirty and twenty-five miles 

 respectively. A smaller slaty ridge separates Kdbul from the plain of 



* The same Dr. Falconer informed me, which from its being so generally found 

 along the base of the Himalaya chain, is usually termed sub-Himalayau. 



