From the Dora Steppe roughly down to Sebi the ground consists in the main of reddish- 

 brown Devonian tile and conglomerates of the same kind as on the Minusinsk Steppe. 

 As mentioned above, the strata of this Devonian formation here is interrupted by one of 

 the spurs of the Sayansk mountain range, the so-called Tashkyl and Artool mountains, 

 running in a south-easterly direction from the main ridge. This mountain range is a 

 very important boundary line, forming a natural barrier between the upper and the 

 lower Yenisei basins. These two parts also differ distinctly in point of natural condi- 

 tions, the south-western part being very dr}', approaching much as to climate and general 

 aspect the whole of the Mongolian steppes. 



Fig. 60. Look-out on the Dora Steppe with the Buddhistic temple 



— the Kuree of the Soyotes — forming the extreme limit of the 



progress of the expedition south-eastwards. 



The Bei-kem 

 valley between 

 Sebi and Tapsa. 



Towards the region where the river runs into these mountains, the strata of the 

 Devonian formation become more and more displaced, with fine folds in the profile along 

 the river. In several places they are seen to have been broken up entirely or raised on 

 edge. Below Sebi, the eruptive zone itself begins, continuing roughly as far as Ujuk. 

 The average breadth of the mountain range here is 60 wersts, the Bei-kem running all 

 this way in foaming white rapids in deep, narrow clefts, with steep, rocky walls on both 

 sides, reaching right up to the regions of tke perennial snow. The roar of the mighty 

 river, averaging here 20 wersts an hour, is echoed from the surrounding mountains, 

 and the lonely travellers feel oppressed by the gloomy, wild and mighty scenery. 

 During our journey here we had also heavy torrents of rain, with hazy weather, contri- 

 buting to make it still more wild and adventurous. At the mouth of the Utt, mighty 

 green porphyrities are seen extending down towards Utinski porgg, followed down- 

 wards successively by gneisses, granites, diabases, and melaphyres, whereupon porphy- 

 rities again appear. The mountain range here has the same character as the Sayansk 



90 



