88 The Amen'c<(n Geologist. Au^'u^st, i»95. 
In order that the sections in southwestern Missouri might 
be accurately eorrehited with the typical localities as a basis 
for future detailed work, the Lower Carboniferous strata were 
carefully traced from Iowa southward along the eastern bor- 
der of the state, all the original localities were examined in 
detail and full collections of fossils made. From northeastern 
Missouri the strata were similarly traced across th? state into 
the southwest. The Kinderhook, upper Burlington and lower 
Burlington limestones were found to extend the entire distance 
with almost no lithological or faunal chang?. But with the 
Keokuk and higher formations of th^ Lower Carboniferous, 
which are so well displayed in southeastern Iowa, som? start- 
ling facts developed in progressing southwestward. After 
passing the Missouri river where, at Boonville, these rocks 
occur with abundant and characteristic fossils, the Keokuk 
beds soon vanished. At Sedalia and for lifty miles beyond no 
Keokuk or higher beds of the Lower Carboniferous limestone 
appeared to be exposed ; and the Coal Measures rested directly 
upon the Burlington. This was indeed clearly demonstrated 
by Broadhead* nearly a quarter of a century ago. It is at 
this part of its southwestern extension, in Pettis, Benton and 
St. Clair counties, that the Lower Carboniferous zone abruptly 
narrows from a width of 75 miles on the north and tlie south 
to less than a dozen miles. At some points the belt is reduced 
to a mere thread, as it were, that is, with only a limited ver- 
tical exposure disclosed by some stream, the Chouteau lime- 
stone being below and the Coal Measure shales in the blutfs 
above. Such a place was at the Osage river. Repeated 
searches and rather extensive collections of fossils from the 
various levels failed to disclose anything of the Lower Car- 
boniferous above the Burlington. 
Probably the feature which most disguises the Lower Car- 
boniferous rocks of southwestern Missouri is the great preva- 
lence of chert; and in the absence of a careful examination of 
the fossils much ditticidty has been encountered in the inter- 
pretation of the stratigraphical problems presented. Further- 
more, it is a striking fact that of all the references to the 
geology of the region under consideration no definite mention 
^Missouri Geol. Sur., Report on Iron ores and Coal Fields. Pt. II. pp. 
1G2. New York, 1873. 
