GEOLOGICAL HISTORY OF AFGHANISTAN. 



77 



It must be admitted that our knowledge of the geology of Afghanistan 

 is so extremely small that many stratigraphical horizons, which are no 

 doubt present, are still undiscovered, and this may be one of them- 

 In Darwaz the Lower Triassic facies described by Dr. von Krafft is 

 entirely different to the Himalayan, and, as what little evidence there is 

 points to a certain similarity between the respective conditions prevailing 

 in Darwaz and Afghan Turkistan towards the close of the Pakeozoic 

 era, I am inclined to regard the Kabul area as the western limit of the 

 Lower Triassic Tethys of the Indian province. 



In Darwaz and other parts of Russian Turkistan volcanic activity 

 began in the latter part of the Fusulina limestone period, and traps and 

 tuffs were interbedded with, and succeeded, the limestone without appa- 

 rent break. Similar' conditions may have prevailed in parts of Afghan 

 Turkistan, but there is no evidence of this, and in Saighan there was a 

 marked break in continuity of deposition, for the volcanic beds overlie 

 the older formations with unconformity and overlap ; the gap thus 

 produced may perhaps have been filled by Lower Triassic beds, but 

 none such have been found as yet, and the question must remain for the 

 present one of the unsolved problems in Afghan geological history. 



This is the second break in the local geological record. It was 

 succeeded by a period of considerable instability characterised by volcanic 

 activity and oscillation between marine and terrestrial conditions. 

 Certain of the beds of dark shale in the Doab series of Saighan are. 

 apparently normal marine sediments, and the accompanying beds of 

 stratified volcanic ash are also evidently of aqueous origin. In other 

 parts of Saighan, however, we find evidence of terrestrial conditions in 

 the local erosion and overlap in the middle of the Doab series itself. 

 Volcanic beds have not been recorded at any appreciable distance to the 

 north-west, for Mr. Griesbach makes no reference to tuffs or traps in 

 Chahil and Shisha Walang, where the Doab series appears to be repre- 

 sented by estuarine and shallow-water marine deposits with Halobice of 

 Upper Triassic aspect. These are the only Triassic marine fossils that 

 have been found in Afghanistan outside the Khingil series and, if truly 

 Triassic, will indicate the extension of the Tethys over parts of Afghan 



