168 
ANNALS NEW YORK ACADEMY OF SCIENCES 
Feet Inches 
gradually into No. 4, while at the bottom the deposit becomes 
more and more carbonaceous and is continuous into the coal below. 
The Banc des Chavais changes quickly toward the west, for long 
before the middle of the trench has been reached, this thick part¬ 
ing has been replaced by shale, carbonaceous shale and coal. The 
gradual passage was exposed at the time when Fayol’s work was 
published; now it is concealed by debris, but exposures are com¬ 
plete midway in the trench and there the parting is wanting. 
6. Coal; Banc intermediate .9 5 
Here one finds numerous partings, one of them two inches thick 
and consisting very largely of mineral charcoal (fusain). The 
coal shows the ordinary variations observed in thick beds, for here 
are the dull layers alternating with bright laminse and occasion¬ 
ally a little pot of cannel is seen. The long open pit at the easterly 
end of the trench shows the erosion of this division, to which Fayol 1 
refers. Unfortunately the exposure shows this for little more than 
a score of feet, not enough to exhibit all of the features, and one is 
not justified in attempting to explain its cause. But, whatever 
the eroding agent may have been, it worked in a curious way; for 
the upper surface of the coal is angular, jagged and pockety. 
The whole of the upper part was not removed everywhere, for a 
foot of the top remains, at one place, undercut for several feet. 
The character of the upper surface suggests that the work was 
done after the coal had become well consolidated. The bed has 
been replaced by imperfectly consolidated stuff like that from a 
collapsed roof. If the exposure were merely an outcrop, one 
would think this rubbish only the remains of a comparatively 
recent slip; but this is a fresh exposure on the edge of the mass, 
which is reported by the miners as extending more than 150 meters 
along the strike. 
7. Shale, Banc des Roseaux .6 in. to 1 6 
A more or less sandy, light-colored to drab shale, very variable in 
thickness and containing great numbers of plant impressions 
beautifully preserved. 
8. Coal, Banc inferieur .11 9 
In great part, this is good coal, but it has many and irregular part¬ 
ings, sometimes becoming so thick as to detract seriously from the 
worth of the bed. The lower limit cannot be determined, for the 
rocky plates and lentils increase and there is gradual passage to 
No. 9. 
9. Coal and rock, Banc du mur, Banc des Brouillages .6 0 
The thickness as given is only approximate. The mass is similar 
to that seen at the extreme w T est end of the trench and consists of 
alternating layers of coal and clay or sandy clay, with here and 
there some rather coarse brecciated beds. Midway in this trench 
the whole of this division has been removed and sandy clay is 
exposed, as follows. 
1 Commentry, p. 274. 
