326 THE TUNDRAS AND STEPPES OF PREHISTORIC EUROPE. 



of the subarctic steppes which are of most importance from our present 

 point of view. 



1. Steppes, like tundras, are not exclusively plains. They include 

 rocky uplands and hills, and are traversed in many places by streams 

 and rivers. 



2. Vast expanses are clothed with grasses, while others are more or 

 less sterile and bare. Oases of forests are not infrequently present. 



3. The most characteristic animals are jerboas, pouched marmots, 

 bobacs, and others — the mammalian fauna being more varied than that 

 of the tundras. 



4. Many animals properly belonging to forest lands and to mountains 

 frequent the steppes. 



5. The seasons are strongly contrasted, and the whole region is 

 exposed to dust storms in summer, and to snowstorms in winter. 



With these facts relating to existing tundras and steppes kept in 

 view, let ns now examine the evidence adduced by geologists to show 

 that tundra and steppe conditions have successively prevailed in Middle 

 Europe. 



One of the most remarkable superficial deposits of central and west- 

 central Europe is that which is known under the general term of loss. 

 Typically it is a fine-grained, yellowish, calcareous, sandy loam — con- 

 sisting very largely of minute grains of quartz, with some admixture of 

 argillaceous and calcareous matter. Upon the whole the quartz grains 

 are well rounded, although often enough they are sharply angular. 

 Frequently the accumulation shows a porous structure, and is pene- 

 trated by long, approximately vertical root-like tubes or canals, lined 

 with calcareous matter, which cause the deposit to cleave or divide in 

 vertical planes. Hence it usually forms more or less upright bluffs 

 upon the margins of streams or rivers which intersect it. It is usually 

 un stratified, except now and again toward the bottom of the deposit, 

 where intercalated layers, and even sometimes thick beds of sand, make 

 their appearance. The loss is essentially a deposit of the low grounds, 

 and is well developed in the broad river valleys of western and central 

 Europe, as in those of the Seine, the Garonne, the Rhone, the Maas, 

 the Moselle, the Rhine and its tributaries, the Danube and many of its 

 affluents, such as the Drave, the Save, the Morava, and the Theiss. It 

 also extends as a narrow belt along the southern margin of the great 

 plains of North Germany. It is in southern and southeastern Russia, 

 however, where it attains its widest development, covering as it does 

 an immense tract, stretching west and east between the valleys of the 

 Pruth and the Volga. Throughout this vast region it is usually very 

 dark in color, forming what is known as the black earth. 



Without at present going into the question as to the origin of the 

 materials of which the loss is composed, it is obvious enough that they 

 have in some places been arranged by water. Thus here and there, 

 especially at or toward the bottom of the accumulation, distinct traces 



