LOFTUS TURKO-PERSIAN FRONTIER. 299 



chiefly consists of pebbles derived from the adjoining igneous chain. 

 This fact is of considerable importance, as tending to establish the 

 fact of the very recent elevation of the Frontier chain, — subsequently 

 indeed to the deposition of the sandstones and associated gravels. 

 It is moreover evident that crystalline action preceded the deposition 

 of the lowest beds of sandstone and gravels, since all the contained 

 limestone-pebbles show that they were altered and rolled before they 

 were imbedded in the matrix of the gravel. 



At the N.W. end of the Desht plain, and at the head of the 

 ravine through which the Shaher stream flows to Uriimia, a spur 

 projects from the great range, and shows the metamorphosed blue 

 limestone resting on pinkish quartz-rock. 



Quitting the Desht plain, the road follows up a narrow ravine 

 formed by the junction of the gypsum-sandstones on the east with 

 underlying blue limestone on the west. 



A low ridge of the same limestone is afterwards crossed, and the 

 plain of Mergaver entered. This plain is bounded on the east by 

 the sandstone and conglomerate hills ; and a patch of the same 

 rocks is crossed just before entering the ravine of the Jura stream, 

 which separates the plains of Mergaver and Beradiist. 



The mountain-masses which occur between Mergaver and Gawar 

 do not present any conspicuous peaks, but consist of a series of vast 

 undulations, across which but few roads are found, and these only 

 along the watercourses. In the transverse section there are shown 

 two eruptions of igneous matter ; a rock of massive hornblende at 

 Bird 1 Resh, and a rounded peak of granite to the west of Dayra. 



On entering the gorge of Arzin by the Jiira ravine^ on the east of 

 the chain, the first rock met with is a cream-coloured limestone, 

 having its layers much broken and presenting some rugged peaks. 

 The colour of this limestone changes from cream-colour in its upper 

 part to grey and dark-blue beneath. In its lower layers it is of 

 similar character to the crystalline blue limestone of Bisutun, near 

 Kermanshah, &c. All the beds are traversed by threads of car- 

 bonate of lime. 



I have in the section (fig. 15) numbered these beds separately, 

 but I am quite convinced that the blue is only an altered condition 

 of the yellow or nummulitic limestone of the south, caused by the 

 neighbouring eruption of the igneous rocks. I have elsewhere 

 expressed my opinion (p. 280) as to the geological age of the greater 

 portion of the blue limestone ; — there can be no doubt as regards the 

 rock here (as also between Ushnu and Mergaver, and at the black 

 conical peak Seah Kuh, on the west of Mergaver) because it con- 

 formably underlies the yellow limestone, into which it passes by a 

 gradual transition. 



Further up the ravine, the blue limestone is underlaid by blue 

 calcareous schists, into which it makes a very marked passage. The 

 limestone first becomes schistose ; and then in this condition alter- 

 nates with the slates. These are in turn underlaid by dark-brown 

 ironstone-clays. These schists and clays probably represent the 

 marls of the Kirrind and Mahidesht section, p. 275 (Part I.), fig. 9. 



