From the Dora Sleppe roughly doNvn 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 dry, approaching much as to climate and general 

 aspect the whole of the Mongolian steppes. 



Fig. 60. Luiik iPiil on the Dora Sleppe with the Buddhistic temple 



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



progress of the expedition south eastwards. 



The Bei kern Towards the region wliere the river runs into these mountains, the strata of the 



valley helween Devonian formation become more and more displaced, with fine folds in the profile alont! 

 ebi andTapsa. 



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



edge. Below Sebi, the eruptive zone itself begins, continuing roughlv 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 the 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. .\t the mouth of the Utt, mighty 

 green porphyrities are seen extending do^^ n towards Utinski porog. 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 



