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Association of American Geologists. — oe 
. sah of th country represented, together. with the most = minent fea- 
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tures in ology and mineral resources of _ sections 
states not yey eee the limits of the m 
Mr. N. then went on to give a succinct account of his geological re- 
e, disclaiming any pretensions to be considered a 
professed geologist * had felt an irresistible inclination to engage in, as 
a subject of gaierel and growing interest. ‘This account he offered as a 
more appropriate theme, in view of the objects contemplated by the pres- 
ent meeting. 
Mr. N. said he had traced a magnesian limestone—the cliff limestone 
of Dr. Owen—which is probably referrible to the mountain limestone of 
European geologists, over a vast extent of country, within the valley of 
ur western 
Owen and Prof. John Locke, and with the observations of Dr. Henry 
King, during an exploration of the country watered by the Osage river, 
Mr. N. thought himself warranted in assigning the Falls of St. Anthony 
on the Mississippi river, as the northern limit of this formation, which to 
the west, extends to Fort Leavenworth on the Missouri river, and to the 
south, embraces the metalliferogs region of the state of Missouri. This 
limestone, containi ilobites, — and other coralline fossils, is 
the metalliferous rock only in Missouri, but in Iowa and Wisttnsia, 
from which the lead and Same ores are extracted. The rock interven- 
ing between it and the coal formation is characterized by the occurrence 
of the Pentamerus oblongus. In this relative position, also are found thin 
beds of oolitic limestone, that are perhaps referrible, geologically, to the 
oolitic limestone of Tennessee, described by Dr. Troost, who indicates the 
pentremites as their characteristic fossil ; a large number of these fossils, 
in a loose state, was collected in the vicinity of these rocks. Shallow 
coal basins Sencently occur in Missouri and the south part of Iowa Ter- 
ritory ; but on the Mississippi river, the coal disappears, about thirty miles 
above St. Louis; thence, ascending the river as far as the great Platte 
river, the cliff limestone and the coal rocks present themselves in alter- 
nate succession. In the vicinity of the Platte river, as well as at Council 
Bluff, a limestone containing cyathophylla of large size, encrinites, and 
other fossils, appears in a position seemingly between the cliff limeatone- 
and the coal. Near the confluence of the Sioux river and the Missouri, 
there occurs a formation overlaid by a thick deposit of clay, containing, in 
abundance, several species of ammonites and baculites, belemnites, ino- 
cerami, &c. &c., beautifully raised on their exterior and sparry in their 
interior. Some of them were exhibited to the meeting. These fossils 
Were identified with similar ones belonging to the green sand deposit of 
New Jersey, a member of the chalk series; but no true chalk or flint 
(silex_pyromage) was observed. The occurrence of this formation had 
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