32 hayden: geology of northern Afghanistan. 



Barakars in lithological character/! As these beds occur more than a 



thousand feet above the horizon of the fossils that he referred to Ilalobta 



lommeli and Monotis salmaria, we now know that it is impossible that 



they could represent part of the Barakar stage, which is entirely 



Pikeozoic. The determination of the lamellibranchs from horizon (a) 



has also been found to require some modification. Unless the sandstone 



from which they were derived was a very thick one, it seemed to me 



improbable that two species characteristic of widely separated horizons 



should occur in the same bed. My colleague, Mr. G. H Tipper, 



has kindly examined Mr. Griesbach's specimens for me and confirms 



my view that neither D. lommeli nor M. salinaria is represented; 



he regards them as perhaps related to Upper Triassic Ilalolue, but 



their affinities are uncertain, and they may be even younger In 



Freeh's Lethcea Mesozoica (p. 121) the true stratigraphical position 



of these beds has been still further obscured by the substitution of 



77 • linn Ritt" for Mr. Griesbach's " HaloUa lommeli.' 

 « Daonella m>Uca mtt. ioi ij- 



From the observations that I was able to make on trie Sab. Kotal, 

 where my work joined and overlapped Mr. Griesbach's, I have cop "* 

 to the conclusion that the two upper horizons 0) and (c) belong to 

 what I have called the Saighan series. 



In Ao Khorak and on the Sabz Kotal, I found no trace of he 

 volcanic Doab series, which is presumably hidden everywhere by the 

 1 • a mant-bearing beds. Nor does Mr. Griesbach make any 

 °^oU^~e in Chahil. It is of coarse possible that the 

 volcanic element may not have extended into this area and is repre- 

 Lted by shales and sandstones similar to those of the Saighan series ; 

 ut t is "apparently quite well developed at * 



i. • + t* ±Q\ It has not been recorded from Russian lurkis 

 Afghanistan (0, 11 Ud,b uuu ., ,,- o „ TY , p ns 



° . -r ■ „i„ n+ beds which are evidently the same as 



tan, where the Jurassic plant beus, wm _ j 



\ Ivh&n series overlie Carboniferous volcanic rocks (32, 89b). It 



. Weber's original paper is not accessible to me, 



