BOTANY OF LA SAL,L,E COUNTY. 7 



upper Cambrian. This rock forms the bluffs of the 

 Fox river and those of the Illinois from a mile west of 

 Ottawa to Utica 



Below the St. Peters Sandstone we find five or six 

 feet of a very porous, yellowish, arenaceous limestone 

 and below a series of bedded, blue, hard, argilla- 

 ceous limestones, the representatives of the calciferous 

 sand rock of New York. It occurs in the river bottom 

 at Utica and in the north bluff west of Utica for about 

 two miles. It is the well known cement rock from 

 which hydraulic cement a water lime is made. It will 

 be seen from a reference to the tabular view on the 

 next pa^e that the geologic series of the state is 

 marked by the absence of many members and that of 

 La Salle County is still more brief than that of the 

 state. But the reader who would know more on this 

 subject we must refer to the article "Geology" in 

 Part II of this work where these questions are con- 

 sidered. 



Prom the variety of rocks of such widely different 

 ages, it is at once apparent that we must have a great 

 variety of soils, clay, sand, with or without lime and 

 magnesia, and these materials mixed in every possible 

 proportion, with iron, sulphur, gypsum, for this is 

 found all through the coal measures, with or without 

 water and here and there considerable quantities of 

 peat thrown in and some salt and we have the ingredi- 

 ents of an almost endless variety of soil sand accommo- 

 dations for plants of very diverse characters and re- 

 quirements. Nor is this all. The low-lying sheltered 

 nooks of the great valleys are never visited by the ex- 

 treme cold of the high and more exposed prairies and 

 offer a safe retreat for the more delicate of nature's 

 beutiful children. 



