266 ANNALS NEW YORK ACADEMY OF SCIENCES 



On the fifth, sixth and seventh benches, the coal is thrown into com- 

 plex folds, which are faulted, for on the seventh, the sandstone, No. 8, 

 is at only three or four feet above the coal, from which it is separated 

 by shale, rolled into flakes like pastry. The shales, No. 7, are closely 

 plicated as they pass over the folds, but all complexity ends with the 

 sandstone, No. 6, which shows, as the only trace, a crumpling of the thin 

 inclosed shales. The higher beds are regular. The faulting and sharp 

 folding end with No. 6 ; the effects of the lateral pressure were expended 

 on the yielding lower rocks, which slipped and bent sharply or were 

 faulted locally, while the hard upper rocks made simply a broad fold, 

 the conditions in this narrow anticline being precisely those observed in 

 disturbed regions of great extent, where some beds are faulted, crumpled 

 or pushed into pockets, while other and more massive inclosing beds 

 seem to be little aiiected by the disturbance. 



The fold is very narrow. Climbing out of the decouverte at the 

 eleventh bench on the eastern side, one finds the easterly dip already 

 gone, the beds on the twelfth and thirteenth benches show westerly dip of 

 25 to 30 degrees, and this dip prevails to the supposed line of the Bag- 

 naud fault, only a few rods farther east. Just outside of the decouverte 

 is the road from Decazeville to Combes; following that to the summit, 

 one sees fumes issuing from many fissures, while farther west on the 

 hillside is the outcrop in an old decouverte, marked by a broad space of 

 white, whence dense fumes arise constantl3^ Here one looks down on 

 the ventilating shaft of the Bourran mine, now used for removal of 

 waste and the blackband which in that mine covers the coal bed. The 

 coal crops out in the steep road just below an abandoned dwelling, 

 where it is exposed for several rods. The dip is such that, if continued, 

 it would carry the coal far above the Tramont decouverte, barely one 

 fourth of a mile away at the east; but it is interrupted, for Bergeron, 

 Jardel and Picandet have recognized the Bagnaud fault in the interval. 



The Bourran shaft is reached at somewhat more than half a mile from 

 the Domergue. The coal, 40 meters below the surface, is said to be 45 

 meters thick. At the Domergue, the thickness is given as 60 meters, 

 the dip being ignored. At the Domergue, the dip where last seen at the 

 east is 40 degrees eastward; near Bourran, the surface rocks dip between 

 25 and 30 degrees. 



The great decouverte of Decazeville is only 700 feet north from the 

 Bourran shaft. Like the decouvertes already mentioned, it was begun 

 along the crest of a close fold and the old workings were confined to a 

 narrow space on each side of the anticline, where that was at nearly the 

 maximum. The great excavation is farther north and reaches better 

 coal, as this fold, like the others, decreases toward the north ver}'^ rapidly. 



