The Bei-keiii flows liere in some places between high cHffs of sandstone or through 

 ;tn alhivial ])laiii. Iliiouiili which il has dug oul a bed lietwcen high, sandy, terraced 

 banlcs, where the river erodes, hi other places wliere the valley is more open and broad, 

 the river has formed large, flat, moist or even quite swamjjy flood-plains. Similar moist 

 flood-plains occur near Ust Tara-kem, and on the Dora Slcppe at 1*i;tho\v and 

 MosGALEWSKi. Tlicsc swamps are here densely overgrown witii vascular plants and 

 contain an exceedingly rich flora of algae, described by me in an earlier publication. 



Fig. 55. From the Upper Bei-kein, near the Dora Steppe. The banks grown ehietly with larch 

 and birch. In the background dry and scorched slopes of Devonian sandstone. 



In this region the Bei-kem valley lies at a height of from 800 — 940 m. above sea-level. 

 The alluvial sand terraces, with a nearly park-like appearance, being large and level 

 with scattered larches, contain, besides some of the above-mentioned plants frequently 

 occurring in larch-wood, also Leontopodiam alpinum var. sibiricum, being a very 

 common and characteristic constituent of the flora, as for instance on the wide sand terra- 

 ces about the river li. In wood constisting of larch, Belula piibescens, and Populus 

 tremiila, the ground is found over large stretches to be grown with Polygonum undulatum 



85 



