Notes on Geology and Mineralogy of Affyhanistan. 583 



stones derived by some convulsion of nature from the neigh- 

 bouring hills, and consisting of various porphyries, basalt, 

 greenstones, toadstones, and limestones, with occasionally a 

 few fragments of granite. 



These stones are in all probability due to the agency of 

 retiring waters, and are almost invariably rounded as if from 

 long continued attrition. What makes the agency of water 

 the more probable, is the fact, that these scattered stones 

 cease altogether as we recede from the hills towards the 

 southward, and give place to the fine desert sands ; while 

 they become both more frequent, and of larger size, as we 

 proceed towards the rocks from which they have been de- 

 rived. Specimens also occur of rocks which are no where 

 met with in the vicinity, and must have been brought from 

 some distance ; of those for instance lying around Candahar, 

 some are granites whose nearest site is in the Shah-muksood 

 range, about thirty miles distant, and divided from the pre- 

 sent position of the fragments by the river Argandab, and 

 a broken range of limestone mountains. Others again con- 

 sist of porphyries containing glassy felspar 9 augite, diorite, 

 and dolerite, but none of them are observable in situ. 



From the Kojeh Amram range to Candahar, the hills are 

 narrow 7 ridges of limestone, bearing traces in some instances 

 of fossil shells, but the heat which these rocks have gene- 

 rally undergone from the intimate association of trap rocks, 

 has rendered such phenomena almost illegible, the presence 

 of shells being now only traceable on the dark matrix, in 

 white and imperfect figures of crystalline carbonate of lime. 

 The whole of these ranges are accompanied by a low basal 

 or outlying ridge of basalt or greenstone running parallel 

 with the mountains, and associated in some instances with 

 porphyry and common serpentine ; iron pyrites, both cubic 

 and nodular, is abundantly disseminated throughout the trap. 

 The city of Candahar stands in a valley between two 

 parallel ranges of limestone hills of inconsiderable elevation ; 



