STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 423 



The Donetz coal basin in southern Russia was studied in 1892-94 

 by Tschernyschew and Loutougin,-' who published a synopsis of 

 their reports. The Basin occupies much of the provinces of Pol- 

 tjiwa, Kharkow and Don Cossacks, and is drained by the Donetz 

 River, emptying at northeastern corner of the Sea of Azov. The 

 Carboniferous is exposed in an area of not far from 12,000 square 

 miles, but borings through overlying deposits prove that the actual 

 extent is much greater. The deposits are, as described by Murchi- 

 son, in three divisions, but the highest one belongs to the Upper 

 Carboniferous. The divisions are designated C^, Cg, and C3, in 

 ascending order. The measurements by Tschernyschew and Lou- 

 tougin are in great detail and the description notes the lithological 

 character and fossil contents of each stratum. Condensed, the de- 

 scription is Ci, in its lower 4 subdivisions, consists of limestones 

 and silicious marls, rich in marine fossils. Coal appears first in the 

 5th, composed of gray micaceous sandstone with subordinate beds 

 of limestone, arkose and shale ; the coals are thin. C^ is charac- 

 terized by Productus giganteus. 



C2 begins with a mass of sandstone, shale and limestone, in which 

 Productus giganteus is wanting and Spirifer mosquensis is the nota- 

 ble form. Coal occurs in the second subdivision, but the seams 

 rarely attain workable thickness. The third, shales, sandstones and 

 insignificant limestones, has 9 coal seams from 0.35 to 0.75 meter 

 thickness ; though rarely reaching the maximum and varying greatly 

 in thickness, several of these seams are mined extensively. At some 

 localities they are excellent for coke, at others for gas, while at 

 others they are anthracitic. Usually only one or two beds are 

 " workable," but at Ouspensko'ie, there are 8. The fourth sub- 

 division, 320 to 350 meters thick, almost wholly sandstone and shale, 

 has 4 seams, rarely workable and often replaced with shale. The 

 fifth, 250 meters thick and composed of sandstone and shale with 

 about 6 meters of limestone, has 8 seams and is richer in coal than 

 are the lower subdivisions, though the seams are very irregular. 

 The extreme thicknesses in the important seams are 0.7 to i meter, 

 but these in some cases thin away to insignificance. The sixth, 225 



-- T. Tschernj'schew and L. Loutougin, " Le Passin du Donetz," Guide 

 des Excursions, XVI., 1897, pp. 4-10, 12-23, 27-29, 34, 50. 



