66 



Mountain furnaces, and possibly for some furnaces now in blast, 

 no analyses are available. 



Similarly, farther south, along this western border of the 

 Coosa Valley, and running parallel with the Coosa coal field in 

 Calhoun, St. Clair, and Shelby counties, there are numerous 

 long narrow outcrops of Trenton limestone. The Calcis quarry 

 of the Tennessee Coal, Iron and Railroad Company, on the Cen- 

 tral of Georgia Railroad, near Sterritt, is upon one of these 

 outcrops, and furnishes limestone with a very low and uniform 

 percentage of silica and magnesia. Analyses n, 12, 13, 14, 15, 

 and 1 6 exhibit the quality of the reck as received at the Ensley 

 Steel Works, but care is taken at the quarry- to select ledges low 

 in silica and magnesia, and the analyses therefore represent 

 only the selected ledges and not the average run of the quarry 

 as a whole. 



Near Talladega Springs, Marble Valley, and Shelby are 

 other occurrences of the rock, and a quarry a few. miles east of 

 Shelby furnace has for many years supplied that furnace with 

 its flux. The quality of the material here is shown by analyses 

 17, 1 8, 19, and 20, Table B. 



The Cambrian limestones contain generally a very considera- 

 ble proportion of magnesia, and for this reason are not suited 

 for Portland-cement manufacture, though admirably adapted 

 for furnace stone. 



Marbles. Along the eastern border o>f tht Coosa Valley, 

 near its contact with the metamorphic rocks, there is a belt of 

 limestone which, in places, is a white crystalline marble of great 

 purity, as is shown by analyses I to 7, inclusive, o-f Table C. 

 The Louisville and Nashville Railroad, from Calera to Talla- 

 dega, passes close to this belt at many points. This marble has 

 been quairried at several places for ornamental stone. It is 

 mentioned here because it is near the railroad and completes the 

 account of the limestone. 



THE CLAYS. 



The most important clays in the Paleozoic region occur in the 

 Coal Measures, in the Lower Carboniferous, and in the Lower 

 Silurian and Cambrian formations. But, inasmuch as a later 

 formation the Tuscaloosa of the Cretaceous borders the 

 Paleozoic on the west and south, and as it contains a great vari- 



