I9I3-] STEVENSON— FORMATION OF COAL BEDS. 125 



fineness of grain as well as by the condition of the water — quiet or 

 agitated. The finer, lighter materials were carried much farther 

 than the others before reaching the bottom. The basin was filled 

 eventually by detritus from the Colombier at the northeast, the 

 Bourrus at the north and by several less important streams at the 

 north and west; these giving three "zones" of coarse material 

 without coal. Between those " zones " and separated by the Bourrus 

 deposits, are two areas of less coarse deposits, les Pegauds at the 

 east and les Ferrieres at the west, in which the coal beds are found. 

 Petty streams from the north added their quotas, uniting the deltas 

 along the northern border, but practically no material was brought 

 in from the south. The streams were, all of them, short and torren- 

 tial. The delta-character of the mass is shown distinctly in the 

 Pegauds area by the steep dip of the beds, which approximates 

 closely that of neptunian or submerged portions of deltas; by the 

 presence of fragments of coal, shale and sandstone in the rocks 

 proving gradual advance of the delta-plain; by slips, of which the 

 proof is seen in folded shales, local faultings, evidence of movements 

 of yielding materials on a steep slope ; by local erosions ; by the clear 

 evidence of great debacles ; and by the structure of the coal beds, 

 which are not parallel. The absence of horizontal alluvial beds on 

 top is due to gradual deepening of the outlet, which amounted to 

 about lOO meters at the close of deposition. Fayol makes no refer- 

 ence in his work to the Decazeville basin, but, as stated in the report 

 of the Reunion of the Geological Society, his theory was applied to 

 that basin by others, who found the evidence as conclusive as that in 

 Commentry, 



In considering this doctrine, one must bear in mind that the mat- 

 ter does not concern the existence of deltas in lakes, for that has 

 never been disputed. Nor does it concern accumulation of vegetable 

 materials in one way or another on the alluvial deposits of deltas, 

 for that too has never been disputed. Fayol's doctrine is that coal 

 beds, like other transported materials, were deposited as part of the 

 neptunian or submerged portions of deltas. Granting, for the 

 present, that vegetable matter to give such coal beds could be brought 

 in by the streams, the only question for consideration here is. 



