30 



GEOLOGY OF LA SALLE COUNTY. 



24 inches thick, no doubt the equivalent of coals Nos. 

 4 and 5. This shaft is remarkable for the immense 

 bed of shales above coal No. 8, no less than 215 feet in 

 thickness. 



In the north part of Utica Township coal has 

 been dug- by removing- the soil and a thin covering- of 

 hard clay. The coal is about eig-hteen inches thick, 

 and perhaps extends a short distance into Waltham 

 Township. Coal has also been dug- just south of Day- 

 ton, in the Fox river bottoms. 



At Ottawa, to the northeast of the city, the super- 

 incumbent earth, soil, slaty clay and indurated c\3.y, 

 being- removed, and the coal, twenty-two inches thick 

 and underlaid by one-half to one inch of fibrous gfyp- 

 sum, and this by three to eig-ht feet of fire clay, is 

 quarried like rock. 



The clay is usually removed by blasting-, being- too 

 toug-h and hard to be broken up by the plougdi. When 

 wet it has a soapy feel, and has received the common 

 but erroneous name of soapstone, and it is this or a 

 similar clay that fig-ures in our sections as soapstone. 



We have spoken of the strata of La Salle county 

 as lying- in a nearh^ horizontal position, but have men- 

 tioned some facts that imply at least that there are 

 exceptions to this rule. 



If we travel from Ottawa to La Salle we shall 

 find that the St. Peters sandstone rises in the north 

 bluff until at Utica station it is about 100 feet above the 

 level of the station, and in the northwest part of Utica 

 villag*-e (North Utica is its corporate title) we see in a 

 ravine the St. Peters resting- on a thin bedded lime- 

 stone. As we g-o farther west we observe that this 

 limestone rises in the same manner, and at last, about 

 two miles west of Utica station, forms the entire bluff. 

 But scarcelv has it reached this elevation, equivalent 

 to an uplifting- of not less than 400 feet between this 

 point and Ottawa, when it beg-ins to descend toward 



