STEVENSON, COAL BASIN OF COMMENTRY 
193 
floods, they would be tom out by high water and carried down; but even 
then the larger plants would be swept out with coarse materials to be inclosed 
in the sandstones — as Fayol properly emphasizes in another connection. 
On the other hand, if the vegetation had been as dense as imagined, it would 
have resisted even more than ordinary rains on the upper reaches which 
made up the 40 square miles of drainage area. If the rain had been so 
terrific as to tear off the trees and sweep away the undergrowth, it would 
have removed the soil also and ages would pass before return of conditions 
favoring a dense growth. 
The hypothesis is not consistent within itself. The mode in which 
the measures accumulated necessitates a surface incapable of supporting 
dense vegetation; but the supposed vegetation was so dense, that it would 
have been its protection against any but the most terrific series of cloudbursts; 
in case of such a debacle, only a small part of the vegetable matter could be 
deposited as a coal bed, for the trees, making one half of the whole amount, 
would be loaded by materials around their roots, would be snags in the mass 
of detritus and would be buried in the sands; even the twigs and under¬ 
brush would be entangled in the mass, for in the short course of the torrent 
there could be no sorting action and all would be dropped when the flood’s 
velocity was checked on the comparatively broad delta surface. Only the 
very finest material, mineral or vegetable could find its way to the bottom 
of the basin — yet it is certain that the trunks of trees make up a very con¬ 
siderable part of the Grande Couehe. 1 
It is well to remember that the supposed subsidence of tree stems in the 
basin is hardly in accord with observed conditions. Such stems as might 
escape entombment on the delta plain would shoot down with great velocity 
into the Pegauds basin, where at most they would be little more than a mile 
from the outlet toward which the surface water would be hastening. Those 
who are familiar with the western rivers of the United States know well that 
logs and stems float for hundreds of miles and remain long before decaying. 
It is more than probable that most of the tree trunks brought down by the 
torrential streams would find their way along with much of the finer materials 
to the outlet and that only a minute proportion of the vegetable matter 
would be deposited within the basin of les Pegauds. The existence of this 
outlet appears to be ignored by the hypothesis under consideration. 
When one considers the enormous mass of the Grande Couehe, certainly 
not less than 30,000,000 cubic meters, he must recognize that it could hardly 
be derived, except during an inconceivably long period, from such vegetable 
matter as could be washed in from 26 square miles,— two thirds of the rocky 
1 Fayol: Commentry, pp. 144, 145, 152. 
