PAPERS ON GEOGRAPHY AND GEOLOGY 369 



would meet the coal. As it requires about two and one 

 half tons of coal to smelt one ton of the ore it was found 

 cheaper to haul the ore to the coal than to haul the coal 

 to the ore. 



In recent years the ore for these smelters has been 

 brought largely from the zinc mines in southwestern Mis- 

 souri. Since the ore from that region would meet the 

 coal, say of southern Illinois, more conveniently than at 

 LaSalle it seems only reasonable that smelting in those 

 fields will sometime displace the industry at LaSalle. 

 The matter of an early start in the industry and the 

 convenient location with regard to a market for the pro- 

 duct are the advantages that still retain the industry 

 in its present condition of prosperity. Of the ten zinc 

 smelters in the state in 1920, only three, the ones men- 

 tioned above, are located in the north half of the state. 

 The others are in coal mining centers farther south. The 

 plants in the LaSalle region were located there as a re- 

 sponse to the local coal supply. 



3. Cement Manufacturing. 



Of the five cement plants listed in the directory of Min- 

 eral Operators in Illinois in 1920, four are located in or 

 within five miles of the city of LaSalle. A plant for the 

 manufacture of hydraulic cement is located at Utica, five 

 miles above LaSalle; two Portland cement plants are 

 located at Oglesby, just across the river from LaSalle, 

 and one Portland cement plant is located in LaSalle. 



The conditions for the manufacturing of cement are 

 particularly favorable in the vicinity of LaSalle. Here 

 are found the coal, the clay and the limestone, located 

 in the order named, above the others. The clay and the 

 limestone are the necessary raw materials for the mak- 

 ing of the cement, and it is an advantage to have the 

 coal in close proximity to the other materials. From 

 Bailey's Falls on the Big Vermilion river to the mouth 

 of that river, the LaSalle limestone is exposed at the 

 surface. Directly beneath it lie soft carboniferous clays, 

 and still lower are seams of excellent coal. Portland 

 cement is made from limestone and clay, which are 

 ground, mixed in certain proportions and fired. In this 

 industry, as in smelting, more fuel than raw material is 



