5J8 Notes on Geology and Mineralogy of Afghanistan. 



pebbles and boulders, and again each furnishes fresh-water 

 fossils of the same genera, and the same indications of dilu- 

 vial accumulations. The configuration of the defiles ap- 

 pears likewise to be in a great measure the same, presenting 

 alternately broad basins and narrow gorges ; yet for all this 

 I cannot agree with Dr. Lord, that the phaenomena met 

 with are in the least indicative of the former presence of 

 fresh-water lakes, and assuredly the fossils enumerated and 

 adduced by him in support of the hypothesis, are imbedded 

 in strata of an age long antecedent to the time when such 

 fresh-water lakes are supposed to have occupied the Khy- 

 ber Pass. The very position of the strata militates against 

 such views, for they are conformable to those on which they 

 lie, showing that they were deposited previous to the uprise 

 of the secondary rocks. Now the fresh-water shells men- 

 tioned by Dr. Lord, are the same as those discovered by 

 myself in the Bolan Pass, and belong to the tertiary strata, 

 which being conformable to the secondary series, as already 

 stated, clearly proves that such shells must have been im- 

 bedded in those rocks previous to the uprise of the moun- 

 tains and to the collecting of the bodies of fresh-water which 

 are supposed to have existed in the basins of the Khyber 

 Pass ; the shells alluded to are imbedded in rocks which 

 may have dammed up the waters, but assuredly they never 

 had existence in the imaginary lakes.* 



That a violent rush of waters had once passed through 

 both defiles there can, I think, be no reason to doubt ; but 

 it appears to me most probable, that those waters were the 

 waves of that ocean which must have been violently dis- 

 placed at the time when the secondary rocks were thrown 



* If Mr. Benson is correct in assigning some of these shells to living species, 

 the fact would somewhat tend to prove that the climate of the tertiary period in 

 these regions was not very different from that of the present day, while the occur- 

 rence of the wonderful tropical forms so abundant in the strata of the Siwalik hills, 

 would at least prove that it was not colder. 



