282 GEOLOGY OF ILLINOIS. 



North of this, there are no exposures in the bluffs for several miles. Along 

 Ellison creek, the rock does not appear till we reach the east part of township 

 9, range 4, but it crops out in several places on some of its branches. It has 

 been worked in sections 23 and 25, township 9, range 5 ; also in sections 9, 

 20, 21 and 29, township 9, range 4. In the bluffs of North Ellison, section 

 13, and of main Ellison, section 24, of the latter township, there are extensive 

 and valuable quarries. These have been worked for a long time,' and have fur- 

 nished an immense amount of stone, both for lime and for building. Most of 

 the strata here are sufficiently thick for any ordinary use. Section 13 affords 

 an excellent article of building stone, the most of which is light colored. That 

 from section 24, is largely of a yellowish or reddish brown, but otherwise of 

 good quality. Some of the layers are more or less arenaceous. The following 

 section was made here : 



FEET. 



1. Drift 10 to 30 



2. Limestone, with some layers of sandstone too little exposed to be separately meas- 



ured 24 



3. Shales of the Kinderhook group ? 



The quarries on these two sections furnish the principal supply of building 

 stone to the surrounding region for some distance, especially to the south and 

 east. At these localities, fossils are quite abundant, especially crinoids. 



At this place there is a dip of from 2 to 3 to the north or northeast. 

 This inclination carries the beds of the Burlington below the surface, and 

 probably continues to a point near Biggsville, from whence they rise towards 

 the north, thus forming a shallow synclinal. At Biggsville, some forty or more 

 feet of the St. Louis and Keokuk group, overlie the Burlington. The first 

 outcrop of the Burlington to the north, that was observed, was a little to the 

 north of the centre of section 32, township 11, range 4. 



West of this, the first exposure of importance is along the Mississippi bluff, 

 in section 15, township 10, range 5. A short distance east of Sagetown, on 

 the Chicago and Burlington branch of the C., B. and Q. railroad, there are ex- 

 tensive quarries owned and worked by A. Wallbaum, Esq. Work was com- 

 menced here in 1861. The quarries lie along South Henderson creek, one on 

 either side, and to each there is a side track from the railroad. A section 

 from the highest point in the openings to the level of the railroad track, gave 

 the following section : 



FEET. IN. 



1. Drift 20 to 25 



2. Chert and clay in irregular layers 10 4 



3. Limestone and chert in thin layers 21 10 



4. Limestone, mostly good, but in places a little cherty 18 10 



5. Soft sandstone 9 



6. Chert 8 



