34 



HAYDEN : GEOLOGY OF NORTHERN AFGHANISTAN. 



in which case they will be chiefly Jurassic, the lower (volcanic) part 

 being possibly Upper Triassic. 



Red Grit Series. 



In the neighbourhood of Ishpushta the plant-bearing series passes 

 up through brown pebble-beds into a great thickness of intensely [red 

 rocks, consisting chiefly of grit, pebbly sandstone and conglomerate. 

 The same series is found also in the Chahil and Khorak area and in 

 Western Afghanistan, where it was named by Mr. Griesbach the " Red 

 Grit group " ; its appearance is very characteristic and it is always 

 readily recognised, forming, as it does, a striking contrast to the white, 

 grey and black beds of the underlying Saighan series. It has been 

 found in Bamian, lower Saighan, Hajar, Kahmard and Ab-i-Khorak. 

 In central Saighan it thins out toward the west and in the upper part 

 of that valley, in Begal and Khargin, disappears altogether, having 

 been removed by denudation, together with almost the whole of the 

 plant-bearing series, before the deposition of the overlying Upper Creta- 

 ceous limestone. 



The age of the Red Grit series is probably Cretaceous. I had no 

 opportunity of examining it in detail, but it appears to contain very 

 few fossils. I found some hippurites, however, in a red calcareous bed 

 near the top, so this bed is presumably Cretaceous. Mr. Griesbach 

 regarded the series as partly Jurassic and partly neocomian (11, 99) ; 

 this conclusion, however, appears to have been based on the determina- 

 tion of certain brachiopods that he found in beds immediately below 

 the Red Grit series at Firaiman near Mashhad and regarded as a 

 variety of Teralratnla gregaria Suess. These specimens are among 

 his collections in the Geological Museum in Calcutta and I have thus 

 been able to examine them : they appear to me to be identical with 

 Terebratula sella Sow., a common form in the Lower Cretaceous of 

 Europe. They occur in a matrix composed largely of Orbitolina ; with 

 these there is also a fragment which appears to belong to one of the 

 Eudista, possibly Monopleura. Presumably therefore the " Firaiman 



