424 



EUSSIA. IN EUROPE. 



connecting the Don by canal with the Volga. The average volume of water is 

 doubtless sufficient to feed a canal, for Belelubski estimates it at 8,650 cubic feet 

 per second ; but the quantity varies greatly with the floods and dry seasons. Free 

 from ice for about two hundred and forty days at its easternmost bend, the Don is 

 sometimes so low and blocked with shoals that navigation becomes difficult even for 

 flat-bottomed boats. During the two floods, at the melting of the ice in spring and in 

 the summer rains, its lower course rises 18 to 20 feet above its normal level, over- 

 flowing its banks in several places for a distance of 18 miles. But in its irregularity 



Fig. 220. IhTHMUS BETWEEN THE DoN AND VoLGA. 



Scale 1 : 940,000. 



10 i.Iiles. 



its flow resembles that of a mountain torrent. Some of its affluents also almost run 

 dry in summer. In fact, the valleys and ovrags, or water- courses, of South Russia are 

 precisely of the same character as the wadies of certain arid lands in Asia and Africa, 

 the streams of the ovrags being classed as " dry " and " wet," while even the latter 

 are mostly mere rivulets, finding their way with difficulty across the argillaceous 

 soil. JYevertheless the wells sunk 160 to 260 feet deep yield everywhere an abun- 

 dance of good water. 



The most important, although not the most extensive, coal-fields of Russia cover 

 an area of about 10,000 square miles, chiefly in the southern part of the Donetz 



