LOFTUS TURKO-PERSIAN FRONTIER. 249 



The journeys of the English Commission, and my own when on 

 detached service, extended, however, as far south as Shiraz (lat. 

 29° 36' N.). Many of my most valuable sections were obtained 

 during these journeys ; and, as they throw light on the order of suc- 

 cession of the different formations upon the immediate line of the 

 Frontier, I have ventured frequently to refer to them. 



If a traveller approach the dominions of the Shah from the Per- 

 sian Gulf, or from Lower Mesopotamia, — that is, between the parallels 

 of latitude of Shiraz and Siileimania (29° 36' and 35° 16' N.),— he 

 must cross the vast range of the ancient Zagros, and invariably meet 

 with the greater portion of the section as exhibited in fig. 1 . Further 

 northwards, however, the igneous eruptions alter and contort the 

 sedimentary rocks in such a manner as to render their recognition no 

 very easy task. I therefore deem it advisable to describe, in the 

 first place, the least complicated and best developed sections in the 

 south, extending as far northward as the A'b-i-Shirwan (lat. 35° 8' 

 N.) ; and, in the second place, to describe certain sections in the 

 north, which throw light on the age of the disturbing forces, and 

 present some interesting phsenomena connected with the deposits of 

 travertin. 



PART I. 



Although contrary to the usual course, I propose describing the 

 various formations in descending order, because they so present 

 themselves to the traveller going eastward, and because this plan is 

 more likely to be serviceable to such European travellers as may feel 

 desirous of adding to our scanty knowledge of the geology of those 

 little-visited regions. 



I. Recent Deposits. 



1. Allvvium. — This term has usually, with regard to the Mesopo- 

 tamian plains, been applied to the soil composing the basins of all the 

 great rivers falling into the Persian Gulf, and extending from the 

 Hamrine Hills, on the east of the Tigris, to the Bahr-i-Nedjef, on the 

 west of the Euphrates. The alluvial formations are, however, much 

 more circumscribed, and do not extend beyond a few miles eastward 

 of the Tigris, where they pass imperceptibly into the underlying 

 light reddish sands or fine gravels of the beds *> of figs. 1 & 2, of 

 which the Hamrine Hills are composed. These older beds frequently 

 dip at an angle of 70°, and gradually become horizontal in their 

 extension westward. The similarity of their general aspect with the 

 alluvial beds, which have chiefly been derived from their denuda- 

 tion, renders it very difiicult to define the exact limit of either 

 formation. 



The alluvium may be clearly divided into — (A.) fluviatile and 

 (B.) marine. 



(A.) The fluviatile alluvium, now in process of deposition, is limited 

 to the banks of the rivers, with the adjoining marshes and canals. 

 It consists of a stiff blue, or fine arenaceous grey clay, and fine sand 

 or gravel. These deposits are dried and cracked in every direction 



