GEOLOGICAL INTRODUCTION 15 



Feet 



2. "Vermicular" sandstone with accompanying shales 



(Northview sandstone), about 60 



1. Tough, bluish-gray, granular limestone (Chouteau lime- 



stone, lower part), about 20 



In Jefferson County, Missouri, 25 miles below St. Louis, the Kinderhook 

 section is as follows : 



SECTION IN JEFFERSON COUNTY, MISSOURI 



Osage group. 



5. Burlington limestone. 

 Kinderhook group. Feet 



4. Red to green, cherty limestone, often very argillaceous, 



(Fern Glen formation) . 30 



3. Fine-grained, yellow or brown sandstone (Bushberg sand- 



stone) . . 14 



2. Sandy shale Ys 



1. Gray or yellowish oolitic limestone (Glen Park limestone), 



about 1 



In Union County, Illinois, in the W. y 2 sec. 11, T. 12 S., R. 2 W., 

 about 3 l /2 miles northwest of Jonesboro, along the creek west of the 

 M. & 0. Railroad track, the Kinderhook has a very different expression 

 from that at any of the points further north, as follows : 



SECTION 31/2 MILES NORTHWEST OF JONESBORO, ILLINOIS. 



Osage group. 



4. Burlington limestone. 



Kinderhook group. Feet 



3. Green, brittle shale 40 



2. Impure, nodular limestone ( ?Rockford limestone) 1 



Devonian. 



1. Thinly laminated, black, brittle, shale, (Chattanooga shale) . . 

 These sections will suffice to exhibit the variable character of the Kin- 

 derhook sediments. Some of the formations, as noted above, have already 

 been given local formation names, and others will doubtless be named in 

 the future, but in no case can any formational unit be traced continuously 

 throughout the entire basin. In the central portion of the basin the Kin- 

 derhook sediments invariably rest unconformably upon subjacent strata, 

 but in the more northern region, as at Burlington, Iowa, and in the more 

 southern region, as in Union County, Illinois, it is not improbable that the 

 sedimentation was continuous from the preceding Upper Devonian into 

 the Kinderhook. It is believed that in early Kinderhook time two distinct 

 basins in the Mississippi Valley were occupied by the sea, one to the north 

 and another to the south of a land barrier, because the faunas of these 



