210 THE TEREK VALLEY. 



of granite. On either side, but more especially on the south, 

 the upper valleys are troughs running parallel to the 

 central chain, and thereby aiding the traveller who wishes 

 to explore it. These upper basins are enclosed between 

 the main chain and the lower but very considerable lime- 

 stone ridges, which guard both its flanks. The rivers 

 rising in the glaciers of the central mass are consequently 

 compelled to make their way to the low country by deep 

 gorges cut through the lateral ranges. In this part of the 

 chain, that is from Suanetia on the west, to the eastern 

 source of the Rion, the relations of the watershed and 

 the two lateral ridges, though sometimes interruj)ted or 

 rendered indistinct (as by the sources of the Zenes-Squali, 

 on the south, or by the great promontory of Dych-Tau on the 

 north), are on the whole easily traceable. The next section 

 eastwards presents at first sight, on the map, a curiously 

 changed aspect ; the watershed having for so large a space 

 run from north-west to south-east, bends suddenly due 

 south, and sinks to the comparatively low gap of the 

 Mamisson Pass. After a few miles it resumes its former 

 direction, but entirely fails to recover its former grandeur, 

 and although the peaks rise frequently to heights of 11,000 

 and 12,000 feet, they support but few and small glaciers, 

 while the passes between them vary from 7,500 feet, the 

 height of the Krestowaja Gora, to 9,000 feet. North of this 

 insignificant watershed, we find a line of summits averag- 

 ing at least 14,000 feet, and terminating in the noble 

 outwork of Kazbek, 1 6,540 feet. A second glance at the 

 map shows that these grand peaks are in an exact line 

 with the glacier-crowned chain which forms the watershed 

 further west, and that the ridge which now divides the 

 basins of the Kur and the Terek is, m fact, the con- 

 tinuation of the southern lateral range. I have only 

 further to point out that the head- waters of the Terek and 



