304 THE JOURNAL OF GEOLOGY. 
proceeded very far. In some places it may, with propriety, be 
called a limestone conglomerate, but from the more or less angu- 
lar character of the fragments the term breccia is more generally 
applicable. In some exposures thin lenticular beds of breccia, iden- 
tical in every respect with the main formation, are intercalated 
between thick layers of the brown concretionary limestone. 
The most prominent fossil found in the brecciated limestone 
is Lithostrotion canadense, though this is not abundant, and 
occasionally another coral like L. proliferum. The latter has 
also been found in the compact limestones at the horizon of the 
brecciated formation, where this formation is absent. The brec- 
ciated limestone characterizes the Saint Louis throughout nearly 
the whole of its extent in southeastern lowa. Except where — 
removed by erosion, and at a few localities (Section V-) where it 
appears never to have been formed, it constitutes a prominent 
feature of nearly all the rock exposures in Lee and Van Buren 
counties. It varies in thickness from five to seventy-five feet, but 
is usually ten to twenty feet thick. 
Keosauqua sandstone——In the area occupied by the Oxbow 
bend of the Des Moines, a bed of rather coarse brown more or 
less friable sandstone is intercalated between the brecciated lime- 
stone and the compact gray limestone above. Below Keosau- 
qua it is seen at several places resting upon the brecciated 
formation with a greater or less thickness of the compact lme- 
stone resting upon it. Above that place it is seen in the south 
bank of the river but little above the level of the water where the 
basal portion is composed in part of isolated layers of limestone 
inclosed in the sandstone. Opposite Keosauqua the deposit is 
much disturbed both in character and stratification, in some 
cases having a large amount of fine calcareous material mingled 
with the sand which is very irregularly lithified, while in other 
cases it contains occasional beds of limestone. The overlying 
limestone has been removed by erosion in some places, leaving 
the sandstone at the surface. The area thus exposed, however, 
is small. In some cases the removal took place prior to the depo- 
sition of the Coal Measures so that now these formations rest 
