121 



But the formations pass over one to the other, and there 

 are species common to several formations. A description of 

 the individual formations such as has been given in the 

 preceeding pages can therefore only present a schematic view 

 of the vegetation. It may bring the physiognomy of the ve- 

 getation more clearly before the reader if I reproduce here 

 a series of descriptions from selected localities in the desert 

 of Transcaspia. 



1. Sand-desert at Tasha-Kirr on the right bank of the 

 Amu Darya. June 22 nd 1899: 



The Sand-desert in this place stretches right down to 

 the river with a high glissade slope, and that this condition 

 has probably existed for a long time may be confirmed a 

 little farther north where there is a long high cliff of sand- 

 stone 8 to 10 metres high. This cliff consists of strata of 

 conglomerate with much sand (the stones attain the size of a 

 bean). Peculiar forms of erosion are shown, low columns and 

 pillars of sandstone crowned with larger masses, probably 

 the remains oi more resistent strata which have protected 

 the lower parts. 



The brown desert behind is very rugged, dune behind 

 dune each with crescent-shaped concavities turned towards 

 SE. Tamarisks grow on the dunes nearest the river-valley, 

 sometimes up to the summits, the bushes being about 2 met- 

 res high. Where the river has eroded the foot of the glissade 

 so that the sand has fallen down, one sees the stems and 

 long roots of the Tamarisks hanging on the slope. 



Farther into the desert, the fresh green colour of the 

 Tamarisks is lacking, but many dead remains of old stems 

 and branches were seen, probably Tamarix. This is a sombre, 

 naked desert formed of large, crescent-shaped dunes. The 

 larger plants stand hundreds of metres apart. The most com- 

 mon is Aristida pennata. None of this plant was seen in the 

 most exposed places, the tops of the dunes. Calligonum and 

 Ammodendron on the contrary defy the most unfavourable 

 conditions and thrive well. Calligonum-bushes were seen on 

 the very tops of the downs, a height of about 2 metres, and 

 there was also a small tree with a stem. Now and again a 

 bush of Smirnowia turkestana was found, its large, vesicular 



