24 



GEOLOGY OF LA SALLK COUNTY. 



a coal seam, then clays and shales, coal, and below it 

 fire clay, the coal being about forty-five feet below the 

 sandstone. 



As we o-o west the strata rise, the sandstone dis- 

 appears, the cla3^s and shales thin out — that is, rise, 

 and the upper part has been carried away, so that in 

 the valley the coal comes nearer the surface, and about 

 a mile and a half northeast of Ottawa is not more than 

 fifteen to sixteen feet below the surface, and a little 

 farther to the west is not to be found. 



In the south bluff it rises much less rapidl}^ 

 not attainingf this elevation until near the South Ottawa 

 Deer Park line, the general make-up of the strata 

 being* the same. About a mile east of Utica station 

 the coal disappears in the north bluff, and is not found 

 there again until a little west of the Utica-La Salle 

 line, just west of the tunnel. At Streator the forma- 

 tion is 211 feet thick, while two miles west of Grand 

 Ridge no coal was found in a boring 300 feet deep, and 

 in places along the Big Vermillion river the Trenton 

 limestone comes to the surface. West of the tunnel 

 and the Big Vermillion river the coal measures thicken 

 rapidly, and a depth of 525 feet has been measured at 

 La Salle, and the strata reported with thickness and 

 character as may be seen, Economical Geology of Illi- 

 nois, Vol. II., pp. 210, 211 and 212. Yet the bottom of 

 the formation was not reached, while in the southeast 

 part of the county it is reported to be 400 feet to coal 

 No. 2. 



In that part of the county north of the Illinois river 

 coal is found as far north as Dayton, in the Fox river 

 bottom, and as far as the north line of La Salle Town- 

 ship, on the Illinois Central railway, about two and 

 three-quarter miles from the La Salle station. In 

 Utica Township coal has been dug in the north part of 



