336 The American Geologist. May, i893 
thin band of sandstone. The almost utter absence of sandstone 
in the Pierre of this section is very noticeable, since sandstone 
enters so largely into the composition of the same formation farther 
west. 
No. 7. — Apparently the same as No. 5, giving theOdanah series 
a thickness in this well of 292 feet. 
Nos. 8 and 9. — In all probability these are both included in the 
Millwood series, representing the lower dark gre}' shales of the 
Pierre formation. The "boulders" are nodules of calcareous iron- 
stone such as are found in abundance in this formation on the 
banks of the Assiniboine river, in the vicinit}- of Millwood. Some 
shells of spiral gasteropods are stated to have been found at a 
depth of 845 feet, but none were seen by the writer. 
No. 10. — This band has been placed at the base of the Millwood 
series, which thus is given a thickness of 664 feet, but some or all 
of it may more properly belong to the top of the underlying Nio- 
brara formation. If it were given the latter position it would 
represent the band of dark unctuous clay with much carbonaceous 
matter, etc. , that is placed at the top of the Niobrara formation 
in Messrs. Meek and Hayden's Missouri section. A specimen 
from 1010 feet consists in part of a soft bluish-gre^' cla}' shale, and 
in part of a light grey cla^-ey limestone. Another specimen from 
near the same depth contains a considerable amount of crystalline 
pyrite. 
No. 11. — A verj' dark grey, soft, unctuous, and very slightly 
calcareous clay shale, containing a few fragmentary remains of 
fishes, and at the top a few foramiuifera {Anomalina sp.),with the 
cells filled with pyrite. Mr. Hoffmann, of this Survey, states that 
the loss from this rock on ignition is 18 percent., representing 
the amount of carbonaceous matter and water in the dried ma- 
terial. 
This band has been placed at the top of the Niobrara formation 
in the section, as it is the highest bed from which foramiuifera 
have been definitely recognized. 
No. 12. — A mottled grey calcareous shale or marlite, contain- 
ing, in varying numbers, foramiuifera, prisms of the shells of 
Inoceramus^ fragments of fish remains, cr3'stalline masses of P3'rite, 
occasional fragments of the pearly shells of Ostrea, and cr^'stals 
of selenite. The following list gives the results of the examination 
of the specimens from every five (or ten) feet: — 
