3o8 The American Geologist. ^^^■^' ^'^'^^• 
of the lowan ice epoch supervened, resulting in the fihing; of 
the ]\Iissouri valley with the lowan loess and its abundant 
waters. 
That "the little relic-bearing deposit" which contains so 
much limestone debris was formed when the limestone was un- 
covered, and by an agent that came into contact with it, is evi- 
dent. The little creek at no place comes into contact with the 
Carboniferous limestone above the point A of figure 2, and that 
point is too low to have furnished this debris, by any agent. 
At no higher point is the limerock uncovered so that any agent 
could get access to it, but loess covers it deeply, even on the 
summit of the bluff back of Concannon's. It appears a neces- 
sarv inference, therefore, that the limestone debris was accum- 
ulated cotemporary with the formation of the loess which now 
covers it and encloses its fragments. 
Plate XVIII. 
V^iew of the face of the tunnel at 72 feet from the entrance, show- 
ing the position of the skeleton with reference to the various members 
of the "Stations" of plate XVII. The white horizontal spot "at the 
right of the hat shows where the bones lay, in fine grajash colored 
material." — M. Concannon. The dark spot above and at the left of the 
hat shows a large limestone mass. The material 4? is probably Car- 
boniferous shale not much disturbed, but perhaps sUd from its place 
and overlying a layer of ic. The "grayish material" in which the 
bones lay, judging from the gray material left in the angle of the wall 
where the Fowke tunnel to the east was begun was a mixture of shale 
and fine limestone gravel, quite compact, impervious and vertically 
jointed, like much of No. i. evidently a more immediate product of the 
disintegration of the shale than any other part of the face of the 
tunnel. 
