102 



which abound in the western dales of Yorkshire, These strata, 

 based upon the crystalline rocks of the southern steppes, con- 

 stitute a greatly disturbed region, and, owing to nmuberless con- 

 volutions, present the most remarkable contrast to the horizontal 

 deposits of Central and Northern Russia. It is therefore difficult to 

 observe the order of succession ; but, owing to our previous acquaint- 

 ance with the types in their normal condition, we were enabled to 

 trace the sequence, from conglomerates and sandstones at the base 

 of the carboniferous limestone, up to the equivalents of the Mag- 

 nesian Limestone or Zechstein. 



Whilst thus briefly alluding to this tract, I must pass, for a time, 

 from my own labours, and those of my friends, of the value of which 

 you must judge when our work is completed, in order to mention the 

 recent appearance of the fourth volume of the splendid work of M. 

 Anatole DemidofF, ' Voyage dans la Russie Meridionale,' which is 

 entirely devoted to the description of the carboniferous region of 

 the Donetz. M. Le Play, an eminent French engineer, happily 

 selected by M. Deniidoff to ascertain the true mineral wealth of the 

 tract, and to describe its physical and geological structure, has pro- 

 duced a work so replete with well-digested details, collected, not 

 only from observations of the natural features of the region and the 

 mines which have already been commenced in it, but also by nu- 

 merous borings carried on by himself or his assistants during a 

 period of thi'ee years, that the Imperial Government will doubtless 

 feel grateful to the accomplished patron who has so liberally fos- 

 tered these inquiries. 



In a large geological map, in which the demarcations of the car- 

 boniferous and crystalline rocks, and also of the overlying secondary 

 and tertiary deposits are given, M. Le Play has grouped under 

 darker colours such parts of the tract as are knowai to be productive 

 of coal, to distinguish them from those in which the mineral has not 

 yet been discovered. This method, doubtless, carries with it a 

 certain amount of information, but is deficient in stratigraphical 

 meaning, for some of the beds so marked are higher than others ; 

 in some the coal is intei^laced with limestone, and in others it is 

 almost entirely subordinate to sandstone and shale ; in one tract 

 anthracite exclusively prevails, in another bituminous coal. By re- 

 ference, however, to the explanation, and to a series of tables, this 

 defect is obviated. These tables are, in fact, perfect models for the 

 practical mining engineer; they give at one view the direction, in- 

 clination, thicki>ess and quality of the coals at each locality, also 

 the characters of the associated strata, as well as the state of the 

 works, and their produce at each mine or trial-spot. To these is 

 added another set of tables, in which the chemical analysis of the 

 coals from forty-three different places is given by M. Malivaud, 

 another agent of M. Demidoif. 



Into such details, valuable as they are, it was not our province to 

 enter, and I will now, therefore, merely offer a few remarks explana- 

 tory of those points in which the geological conclusions of my friends 

 and self either agree pr are at variance with those of M, J^e Play. 



