26 Some Geological Problems — Calvin. 
Mississippi river, from Lansing to Keokuk, for the purpose of 
obtaining a general knowledge of the geological structure of 
the eastern part of Iowa. The same ground had previously 
been traversed, at least in part, by the geologists D. D. Owen 
and B. F. Shumard, and the work of Hall, while correcting 
some mistakes, tended in the main to confirm and establish the 
conclusions of the earlier geologists. Considering the unde- 
veloped condition of the country, the vastness of the field at- 
tempted to be covered in a short time by the surveys of Owen 
and Hall, and the scantiness of the materials for observation 
as compared with those now available in our quarries, railway 
cuttings and other artificial excavations, we cannot but admire 
the skill and success with which the several geological problems 
were worked out. Mi-takes of course were made, mistakes 
were under the circumstances unavoidable. While Hall, by 
reason of better facilities for study, was able to rectify some of 
the errors of his predecessors, he was himself occasionally led 
into error, and one of these errors has been the cause of some 
confasion among geologists. The desire to correct this error 
must stand responsible for the addition of this paper to the 
already overburdened literature of geology. 
In the days of the geological reconnaissance referred to, the 
present town of Buffalo in Scott county, Iowa, was known as 
New Buffalo. New Buffalo figures in all these earlier reports, 
for near the village occurs an interesting fossiliferous lime- 
stone, exposed along the river or in the sides of the ravines; and 
the reports of Owen and Shumard* and Hallf are in accord in 
referring this limestone to the age of the Hamilton group of 
New York. 
The Hamilton limestone of Buffalo with its peculiar associa- 
tion of fossils, disappears beneath the level of tlie river at or- 
dinary stages a short distance below Montpelier in Muscatine 
county. The last seen of it in that immediate region, it forms 
a low ledge or reef, exposed at low water, and running out into 
the Mississippi river a hundred yards or more at a point almost 
directly in front of the present residence of Mr. G. AV. Robin- 
son. If, however, we follow the bank of the Mississippi, we 
♦Owen's Geological Survey of Wisconsin, Iowa and Minnesota, Phila- 
delphia, 1852. 
•(■Report on the Geological Survey of Iowa, by James Hall, 1858. 
