B. H. Howorth—A Great Post-GIacial Flood. 73 



Been. Two miles from Laureana, the swampy soil in tioo ravines 

 became filled loith calcareous matter, which oozed out from the ground 

 iwmediatehj before the first great shoclc. This mud rapidly accumu- 

 lating, began ere long to roll onward, like a flood of lava, into 

 the valley, where the two streams uniting, moved forward vpith. 

 increased impetus from east to west. It now presented a breadth 

 of 225 feet by 15 in depth, and before it ceased to move covered 

 a surface equal in length to an Italian mile. In its progress it 

 overwhelmed a flocJc of 30 goats, and tore up by the roots many olive 

 and mulberry trees, which floated like ships upon its surface " (Lyell's 

 Principles of Geology, vol. ii. p. 133). 



The theory receives support in another way. Hardly less puzzling 

 than the Loess, in fact more so, is the vast deposit of black earth 

 which occurs in Central Russia, and which is known as Tschernozom 

 or black earth. It has exercised the ingenuity of various inquirers, 

 and still demands an explanation. Its northern limit, according to 

 Murchison, may be defined by a wavy line passing from near Kief 

 and Tchernizof, a little to the south of Lichvin. It appears in 54° 

 N.L. in that tract, and advances in its course eastwards to 57°, and 

 occupies the left bank of the Volga west of Tchekboksar, between 

 Nijni Novgorod and Kazan. Murchison saw none of it north of 

 Kazan, but plenty of it on the Kama and the Ufa. On the Siberian 

 side of the Urals he passed through a large mass of it near Kamensk, 

 south of the river Isoetz, in latitude 56° north, and through another 

 between Miask and Troitsk, and he was given to understand that 

 it spreads over considerable spaces in the eastern, central, and 

 southern parts of the great Siberian plains. He met with it 

 occasionally in the low gorges of the Urals, and in the Bashkir 

 country on both flanks of the Southern Ural (in plateaux more th.an 

 1000 feet above the sea), and also in the Kirghiz Steppes. 



The distribution of the black earth is singularly like that of the 

 Loess, its texture is like that of the Loess in being comminuted 

 and fine, especially the siliceous part of it. Like the Loess, it is 

 found at all levels in European Russia, sometimes on plateaux 400 

 feet above the valleys, in other places on undulations, and often in 

 broad valleys where the rivers having cut through the deposit 

 expose its thickness. It is like the Loess in being unstratified, and 

 in being everywhere homogeneous. Its position relative to the 

 drift and river gravels is that of the Loess, for, except at one spot, 

 near Voroney, mentioned by Murchison, it overlaps the drift, and is 

 subsequent to it. In every respect, save its dark colour and the 

 material of which it is composed and in its contents, it is the exact 

 counterpart of the Loess. Schmidt identifies the black earth of 

 Russia with the Loess, and says it is substantively nothing but Loess 

 (Letter to Richthofen, Zeits. Deutsch. Geol. Ges. vol. xxix. pp. 

 830-1). Mr. Geikie says of it that it occupies the same geological 

 horizon as the Loess, and that its origin is undoubtedly closely 

 bound up with it {op. cit. p. 157). Like the Loess, it is distributed 

 about an apparently recently disturbed mountain focus, namely, the 

 Southern Urals. What are we to say then about the origin of the 



