186 
ANNALS NEW YORK ACADEMY OF SCIENCES 
and the mass decreases southwardly until it disappears more than half way 
from the southern border. In the earlier days it was supposed to be a primi¬ 
tive rock, but Fayol’s studies disclosed its true character. Its outcrop is 
five kilometers long and the content is estimated at 125,000,000 cubic meters. 1 
The writer made only cursory examination of it near Chavais. 
The map of the Commentry basin, Figure 1, shows approximately the 
extent of the several zones or areas of deposit. By careful study of frag¬ 
ments, Fayol was enabled to determine the source of materials found in each, 
to reconstruct the drainage system and to follow in detail the gradual filling 
of the basin. Figure 3 shows his conception of the drainage area. 
FIGURE 3. THE DRAINAGE AREA OF LAKE COMMENTRY. A, GNEIS-S; B, GRANITE. 
Reference has been made already to de Launay’s recognition of a double 
trough extending northeastwardly from near Monthu^on toward Moulins, 
60 kilometers away, the divisions being separated by a granite crest. The 
western division is limited at the northwest by a fault of 200 meters, which 
is distinct in the northerly portion but not in the Commentry region; there, 
however, the western border of the basin evidently coincides in direction 
with the fault, and the coal measures there as well as at the south, are in 
contact with the granite as appears from de Launay’s map. The syncline 
was divided by westward movement of the granite into several petty basins 
which were afterwards filled by lakes. 2 
Fayol’s conception is that of a lake, nine kilometers long, three kilo¬ 
meters wide and 800 meters deep, surrounded by steep mountains on almost 
all sides. Les Bourrus at the north and Colombier at the east were the 
valleys whence came the chief affluents; some narrower valleys, Chamblet 
1 Fayol: Commentry, pp. 96-102. 
2 De Launay, L.: Reunion etc., pp. 98-100 
