240 GEOLOGY OF ILLINOIS. 



part of the river which runs near the west line of the section appear to 

 be the same just referred to. In the bend of the river at the middle of 

 the north-west quarter of sec. 9 the strata of sandstone and shale dip 

 about west one foot in twenty. Ten rods further up the river the dip is 

 a little south of east at the same rate. 



Near the south line of sec. 9 the same sandstone shows again, and 

 dips south-easterly. In the bank of the river in the S. E. qr. of sec. 16, 

 the S. W. qr. of sec. 15, and the 1ST. W. qr. of sec. 22, the limestone 

 before referred to appears in loose masses, the banks formed of the 

 underlying blue clay. A slippery bank, and the limestone slipped down, 

 is, everywhere it appears, characteristic of this portion of the vertical 

 section, often obscuring the details. Near the north line of sec. 22, and 

 a quarter of a mile east of the north-west corner, the limestoue in place 

 is down to the river level. The character of this rock to disintegrate 

 into irregular fragments is exhibited here in abundant loose, coarse 

 limestone gravel, two to four inches in diameter. 



From this point to Allen's mill, in the south-west quarter of sec. 23, 

 nothing noticeable is to be seen. This limestone appears again at the 

 mill-dam, and also at the ford, two miles and a half below Poutiac, and 

 at Poutiac. The fossils are Spirifer cameratus, S. liiucatus, S- plano- 

 convextis, Productus longispinus, and Belleroplion. 



The branches of the river in this county afford no aid in determining 

 the rock strata, excepting at a very few points, the drift concealing 

 everything below. Above Pontiac but little rock exposure is found. 



The details given of the tracing of the river up to Pontiac show the 

 upheaval of the Coal Measures continued as in LaSalle county, and 

 also seem to indicate some slight local disturbances or parallel axial 

 Unes with the main axis. 



On Book's creek, in the N. W. qr. of the K E. qr. of sec. 23, T. 28, E. 



4 E., a sandstone is quarried. The section is as follows: 



it. 



Sandstone in thin laminaa 5 



Sandstone in thick beds, slightly micaceous, bluish color, fine building stone _ 2 



Shaly sandstone to "n-ater level 1 



DipS. SO W 1 in. to 1 



One hundred yards west, down the creek, it shows again. Two hun- 

 dred yards west, on the left bank of the creek, a limestone comes in, 

 stratified in masses, brecciated, about five feet altogether — no fossils. 

 The sandstone shows again in the bed of the creek about 80 to 100 rods 

 in a south-east course. 



Section of coal shaft at Pontiac, as furnished from the record of the 

 company : 



Ft. In. It. In. 



1. Driftelay IS 9 



2. Limestone 1 5 20 2 



3. Blueshale 5 25 2 



