300 The American Geologist. ^°^^'' ^^^^• 
ficd substance 4a (in the j^ilate may he Carljoniferous shale in 
situ, but as it shows rather too much dii) and as no shale ap- 
pears at the nearest point in the wall it may be 4a of the fore- 
going stations. In the latter case the designation ic is the 
lowest geest stratum. In any case the mass of the geest is 
above 4a and the skeleton lay in or on it, some of the limestone 
slabs of the geest lying at a little higher level than the skeleton. 
In No: 2 are scattering bits of charcoal, and some land shells, 
viz : Polygyra exoleta, Pyramidula alternata costata, Polygyra 
monodon fraterna, and Pyramidula perspectiva, and fragments 
of small bones. 
The bluffs of the Missouri river. 
The writer made examination of the river blufifs above and 
below the Concannon farm. There are five benches, four of 
which might be mistaken for alluvial terraces, numbered from 
below upward. 
These are all more or less continuous both above and below 
Concannon's, but Nos. i, 3 and 5 are distinctly marked and 
level. 
Level No. i. By excavating in No. i it was found to con- 
sist of fine sandy alluvium appearing clayey when wet. It 
covers the place of the stratum of limestone that forms the floor 
of the tunnel. It was at first suspected that its existence was 
due to the persistence of that stratum, but that idea was aban- 
doned after seVeral pits had been sunk in it, and on observing 
that at no point, for three cjuarters of a mile below, nor for 
two-thirds of a mile above, does that limerock appear in any 
of its angles. This terrace is well showai in professor Cham- 
berlin's photographic figure No. 6 (p. 757), running but little 
above the grade of the railroad. Its level is fifteen to eighteen 
feet above the bottom land, or thirty feet above low water. Its 
width is twenty to forty feet. 
Level No. 2, is irregular and hummocky as to upper outline 
and suggests a slip origin. It rises twelve to fifteen feet above 
No. I and its width is about twenty-five feet, but in spots it is 
wanting, the ground sloping up from Level No. i to No. 3. 
Large fallen masses of limestone more or less disintegrated lie 
on the surface, or are buried in soil and vegetation. From this 
bench to No. 3 is a sharp ascent to No. 3, which latter shows 
