LOFTUS TURKO-PERSIAN FRONTIER. 293 



of the Derbend these rocks appear to have been thrown down by a 

 fault, and present a bluff escarpment to the west ; while on the left 

 bank of the stream the white limestone rests upon the flank of the 

 limestone-beds of the U'shteran Kuh, from which they seem to have 

 slid down to their present position. 



Fossils are entirely wanting in all these altered rocks, but I believe 

 that the slates of Japiilak plain belong to an early series, and are of 

 the same age as the Elwend slates. 



The white limestone and blue clays of the Derbend I am inclined 

 to assign to the age of the cretaceous deposits ; while the beds of the 

 U'shteran Kiih are probably lower secondary. The last, however, I 

 had no opportunity of reaching. 



As to the date of the eruption of the granitic chain, there can be 

 no doubt of its having taken place subsequently to the deposition of 

 all the rocks in the vicinity ; and, although no positive evidence 

 exists of the fact in this portion of the region under examination, 

 there is every reason to pronounce, from examination of other 

 localities, that it occurred after the formation of the Nummulitic 

 and Gypsiferous series, and after the accumulation of the compara- 

 tively modern gravel-conglomerate on the western outskirts of the 

 whole chain. 



VII. Trappean Rocks. 



Porphyry occurs sparingly on the skirts of the granitic chain, but 

 does not assume any great development. It shows itself in this 

 position in a range of low hills on the S.E. of Nehavend, erupted 

 through, and elevating, altered blue limestone. It is there red and 

 argillaceous, and is associated with serpentine. 



Trap-porphyry occurs in considerable veins on the Western side 

 of the Merwari Pass already alluded to (p. 281 & 292), where it is 

 injected not only through the altered limestone and chert, but also 

 through the syenite and older trap-veins. 



Serpentine is generally met with in the same localities as the trap- 

 porphyry, but is much more abundantly diffused, and frequently 

 forms very considerable sombre-looking peaks, as in the neighbour- 

 hood of Senna. At the Merwari Pass a light-green serpentine in 

 felspar appears to have been injected into the limestones previously 

 to the elevation of the granitic axis (see fig. 1, s) ; and is in turn 

 traversed by veins of newer porphyry. 



The usual kind of serpentine is an exceedingly hard, massive, 

 dark-green variety, accompanied by steatite. 



