300 The American Geologist. May, i899 
from the mouth of the Big Sioux river above Sioux 
City, to St. Louis, down to the present time many 
geological notices have appeared in regard to the geo- 
logical formations bordering the great stream. Most of these 
references, however, have been incidental or fragmentary, 
some alluding to one part of the section and some to another. 
Of all of these Broadhead's* section is the most complete. This 
purports to give a connected succession for a much greater dis- 
tance than any other. Though described in too much detail 
to be applicable over any considerable area, it is, in its main 
features, essentially correct so far as it goes. His correlations 
of other exposures with the Missouri river sections are, how- 
ever, somewhat faulty. 
Nicollet, Owen, de Verneuil, and others believed that the 
formations exposed on the Missouri river were the Mountain 
limestones of the Mississippi, that were brought to the surface 
on the opposite side of a broad syncline the lower portion of 
which contained the productive coal measures of Iowa and 
Missouri. Swallowf appears to have been the first to discover 
that the Missouri river rocks were above and not beneath the 
principal coal-bearing formation of the region. 
Marcou^, Meek§, andWhiteJl and many others who have 
visited the Missouri river have given only isolated, uncorrelated 
sections. Swallow^ and Broadhead**have constructed from the 
various exposures a generalized vertical section; and recently 
Bennettft has, on the Kansas side of the stream, corroborated 
many of the earlier observations of Broadhead on the Missou- 
ri side, though only in a very general way. Of late, ProsserJ;|; 
has recorded some of his observations made in southeastern 
Nebraska, dealing particularly with the uppermost part of the 
series. 
*Geol. Surv. Missouri, Iron Ores and Coal Fields, pt. ii, pp. 80-133. 
1873- 
tMissouri Geol. Surv., ist and 2nd Ann. Repts., p. 81, 1855. 
JBull. Soc. G^ol. France, 2e Ser., t. xxi, p. 137, 1864. 
§U. S, Geol. Surv. Nebraska, p. 87, 1872. 
IIGeology Iowa, Vol. I, p. 369, 1870. 
^Missouri Geol. Surv., ist and 2nd Ann. Repts., p. 78, 1855. 
**Ibid., Iron Ores and Coal Fields, pt. ii, p. 80, 1873. 
ttUniv. Geol. Surv. Kansas, Vol. I, p. 50, 1896. 
jjjournal Geology, V^ol. V, p. i, 1897. 
