COAL: ITS STRUCTURE AND FORMATION. 433 



successive periods come into play ". In his excellent Traits 

 de Geologic De Lapparent 1 enters more fully into the question 

 of coal formation, and states, at some length, the arguments 

 advanced by recent workers in favour of the drift theory 

 or allochthonous origin of coal seams. The tendency in 

 England seems to have been much too conservative with 

 reference to this matter, and it is only by slow degrees that 

 any adequate recognition has been accorded to the strong 

 case against the old orthodox opinions as to the formation 

 of coal. In Solms-Laubach's encyclopaedic text-book on 

 fossil botany we have an extremely interesting account of 

 the present state of our knowledge as to the nature of coal 

 and its manner of production. A sketch is given of Grand' 

 Eury's views, and the geographical and physical conditions 

 are depicted, which seem to have obtained according to the 

 comparatively recent theory of this French savant. In 

 1882 a full account of Grand' Eury's views appeared in the 

 Revue de deux Mondes, written by the ready pen of the 

 Marquis of Saporta. Before noticing some of the more im- 

 portant points in Grand' Eury's arguments, reference must 

 be made to a much earlier work by an English geologist. 

 The importance of Beete Jukes' studies in the South Staf- 

 fordshire coalfield does not appear to have been adequately 

 recognised by English geologists, but in the works of their 

 French confreres we find frequent references to this valuable 

 survey memoir. One of the most striking features exhibited 

 by the Staffordshire coal beds is the splitting of a thirty- 

 foot seam, when traced in a northerly direction, into ten to 

 fourteen distinct seams, separated by intervening beds of 

 sandstones and shales. A section of the strata in one area 

 shows a mass of coal thirty feet in thickness, in another 

 section, not more than five miles in a horizontal direction 

 from the first, the thirty-foot seam has become sub-divided 

 into several beds, which are interstratified in a series of 

 sedimentary rocks three hundred feet thick. This splitting 

 of beds towards a particular direction is "a kind of change 

 quite familiar to those who are accustomed to trace any set 



1 P. 860. 



