Chap. I] THE FORMATIONS 167 



during which the precipitations occur, the finer these precipitations are and the 

 more regularly distributed, so much the more water penetrates into the deeper 

 strata of the soil, instead of running quickly over the ground and filling the 

 rivers. Still better for vegetation is a covering of snow. Whether it fall early 

 or late, the snow always melts in the spring, when vegetation requires most 

 water. The permanent snow-covering of winter is the chief cause of the 

 presence of forests in North Russia and Sweden, although the annual rainfall 

 is much less there than in Western Europe. In the south, in the steppes the 

 amount of snow that falls is much less, and even that which has fallen is blown 

 away by the strong winds and collects in hollows, whilst the ridges remain free 

 from snow V 



' A proof that woody plants exist without summer rain is afforded by the 

 trees that are cultivated without artificial supplies of water in Southern Europe, 

 where during summer frequently not a drop of rain falls for months, and yet 

 even the vine bears plenty of fruit, and for this of course much water is needed. 

 On the south coast of the Crimea, for instance, the vine-growers set not the 

 slightest value on the summer rain ; it has no influence on the abundance of 

 the vintage, for it wets the soil too superficially. It is quite different with the 

 rains during late autumn and winter, which are plentiful enough to render the 

 soil thoroughly wet to the depth of a meter and to yield a supply for the whole 

 of the succeeding summer. 



' Not only vine-growers but all persons engaged in agriculture or horticulture 

 know very well that frequent but light showers of rain do little or no good, and 

 that it is better if in the course of a month there are two rainy days with a 

 fortnight's interval between them, each giving 20 mm. of rainfall, than if the 

 same amount were to fall in fourteen days at the rate of 3 mm. on each rainy day : 

 since in the former case the soil is wetted to a greater depth, but in the latter 

 case the rain-water remains almost entirely in the uppermost stratum of the 

 soil, provided that drought prevailed before the rain fell 2 .' 



'A consideration of the country near the Volga and the Eastern Caucasus has 

 convinced me of the close connexion between the cultivation of winter corn and 

 forest growth. In districts with a cold winter (below o° C.) a continuous snowy 

 covering is necessary, so that the soil in the spring may be completely permeated 

 with moisture ; summer rain cannot compensate for the absence of snow because 

 of the irregularity of its occurrence and the great amount of rain that falls at 

 one time and forthwith runs off without benefiting the soil. 



' In more southern districts regular winter rains are necessary in order to 

 render the cultivation of winter fruits possible. If the rainfall is scanty, cereals 

 will grow and yield a safe harvest, but forests cannot exist. This, for instance, 

 we see on the peninsula of Apsheron. There winter wheat is everywhere 

 sown ; it yields unsatisfactory but safe harvests, for wheat requires moisture 

 only in the uppermost stratum of the soil. If the atmospheric precipitations in 

 autumn and winter are more plentiful, forest vegetation can also thrive. This, for 

 instance, we see at Leukoran. Somewhat to the north of the town are some 

 colonies of Russian sectaries, who sow winter wheat and barley exclusively. 



1 Woeikof, I, p. 243. 2 Id. II, Bd. II, p. 255. 



