STEVENSON, COAL BASIN OF COMMENTRY 
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a wide valley perhaps 200 feet deep, in which at a later time were deposited 
sands and silts; just as has happened within recent time at many places 
within the basin. One of these later valleys has been exposed in the southerly 
portion of the Longeroux trench; it is filled with the gravels of the alluvial 
deposit now covering the basin. 
The Glissement sandstone, containing much kaolinized feldspar and 
for the most part only moderately coarse, was subjected at last to great 
pressure, by which its beds were folded into a complex syncline, while the 
fine shales and the Gres Nobs beyond were pushed into recumbent folds. 
The cause of dislocation. 
This leads to the consideration of another matter. The dip in most 
of the exposed area within les Pegauds is approximately 30 degrees, the 
Grande Couche showing the same dip as the other beds; and this has been 
supposed to be the original slope of the beds. There is no room for doubt 
that beds can be deposited with that slope, especially if the delta be formed 
in a deep water-basin; Fayol has proved this by experiment, but the question 
is not what is possible but what is probable. And there seems to be good 
reason for hesitation before accepting the propositions that the steep dip is 
approximately the original and that the basin was deep. 
There is abundant evidence in many portions of les Pegauds that after 
consolidation the beds were exposed to tremendous pressure such as accom¬ 
panies folding. Even on the westerly side in the trench of Pre-Gigot, the 
black shales accompanying the Grande Couche are rolled in some places 
like pastry and show polished surfaces. Occasionally the coal itself is 
crushed into petty lentils which have been rubbed and polished. It is by 
no means improbable that the curious flexures seen in several beds of shale 
erew due to the yielding and slipping of soft between hard beds. Some even 
of the petty faults with small vertical extent seem referable to disturbance 
after the rocks had been consolidated. The evidences of dislocation increase 
eastwardly, reaching the extreme in the southerly portion of l’Esperance 
and the adjacent portion of Longeroux. 
The disturbance took place after sedimentation had ceased in the area 
examined, and its cause must be sought in the northeast portion of the 
Pegauds area. 
When the basin had been filled, a great outflow of igneous rock occurred 
on the northeasterly side and its dikes extended even into the Trancehe de 
Saint-Edmond, midway along the outcrop. This rock did not break through 
the rocks surrounding the basin, but through the coal measures themselves 
not far from the edge of the Grande Couche. Some dikes appear even in the 
