SAIGHAN SERIES. 



33 



This Mesozoic volcanic phase would therefore seem to have affected 

 a wide area, and it would be rather surprising- to find that Chahil was 

 outside its range. Perhaps Mr. Griesbach, having frequently referred 

 to the presence of igneous rocks in what he regarded as the Trias in 

 other localities, did not consider it necessary to refer to them again 

 or possibly the supposed Halobia are Jurassic. This, unfortunately, 

 is another of the many points in the geology of Afghanistan that must 

 be left for the future — a distant future, I fear — to decide. 



The resemblance, both lithological and floral, between the Saighan 

 series and the plant-bearing beds of Ferghana, Syr Darya and other 

 parts of Russian Turkistan, is so striking that there can be no reason- 

 able doubt that the conditions of deposition were the same in both 

 cases and that the Saighan series belongs to the Angara, rather than 

 to the Gondwana, province. 



Mr. Griesbach, on the other hand, regarded Western Afghanistan 

 and Afghan Turkistan as parts of Gondwanaland, for he believed 

 that his "Plant-bearing series " was the exact counterpart of the 

 Gondwanas of India (11, 98). This opinion was based (a) on the litho- 

 logical resemblance between the basal conglomerates of Palezkar and 

 the Talchirs, and between the uppermost beds at Chahil and the Bara- 

 kars (9, 245) ; (b) on the supposed alternation of the highest beds of the 

 Fusulina limestone series at Ak Robat with conglomerates of his 

 " anthracite series, " and (c) on the presence of fossils referred by him 

 to Vertebraria and Schizoneura. With regard to (a), lithological 

 resemblance between such widely separated areas as the Salt Range 

 and Western Afghanistan is at the best a dangerous guide, and it has 

 been shown above that the correlation between the Chahil plant-beds 

 and the Barakars is untenable ; (b) my observations lead me to infer 

 that the " anthracite series" is older than the Fusulina limestone ; (e) 

 the fossils on which the first of these determinations is based are only 

 indistinct markings, which are quite undeterminable and might be 

 equally well referred to Equwetites, while Schizoneura has such a wide 

 range that it is of no value unless its species can be ascertained. Per- 

 haps, therefore, the western beds are after all the same as the northern, 



V 



