16 F. V. Hayden on the Geology of Northeastern Dakota. 
hereafter aid in the solution of the problem of their age, inas- 
much as their geographical distribution seems to be quite ex- 
tended. 
In October last, after my return from a tour of exploration to 
the “ Manvaises Terres” or “Bad Lands” of White river, I too 
advantage of an opportunity that presented itself to rer some 
portions rof Dakota Territory on the _ side of the Missouri 
river not hitherto examined by me. 1 there made sme start- 
ing point the village of Yankton, the capital of Dakota Terri- 
loeated on the Missouri, about twelve miles above the 
mouth of the James. At this point we observed a large expo- 
sure of the yellow calcareous marl beds of No. 8, Niobrara Di- 
vision, forming along the river ara vertical bluffs, extending 
sometimes several miles. ‘I'he rock varies in texture from a 
nearly white, soft chalk, much like our chalk of commerce, to a 
somewhat compact limestone which is used for burning into lime 
and for building purposes. Thick beds of this chalk present a 
marked nies color from ake presence of a greater or less amount 
of th xyd of iron; otherwise it could hardly be distin- 
guished ones the chalk of Europe, and without doubt would 
serve the same economical purposes. The organic remains found 
here are not very numerous in species. The most abundant 
shell is the Ostrea rece Conrad, which seems to have been 
as gregarious and to e aggregated together much in the same 
way as the little opens iekioh is exposed when the tide recedes 
‘along the shores of the Sea Islands of South Carolina. Near 
the base of No. 3, there are layers of rock several feet in thick- 
ness, made up almost entirely of one or more species of Jnoce- 
ramus, one of which has been identified as J. problematicus. The 
fish remains are quite numerous, diffused throughout the rock. 
Fragments, consisting of jaws, ribs and scales, are found in the 
greatest abundance, and Mr. Propper, = ie of Yankton has 
eded in securing some nearl pecimens (unde- 
scribed) from the quarries eae bie om af if oben extends 
for four hundred miles along the Missouri river, and I am con- 
vinced that when carefully studied, it will be found to represent 
the _ Chalk beds of Europe, ‘and be employed for similar 
econom urposes. 
The Cretancoal rocks of the Missouri river ape been num 
bered in the order of superposition, Nos. 1, 2, 8, 4, 5, and all 
of these divisions have been located in oti "geological scale by 
the unmistakable evidence of their organic remains. We fin 
therefore that this portion of Dakota is occupied pins aitagl or 
nearly so, by the middle member of the Cretaceous series. The 
soft and yielding nature of No. 8 is well shown - the topo- 
 , features of the country, where all the slopesare gentle 
ir descent, and for the most part covered “i a a Xs 
