336 CEMENT MATERIALS AND INDUSTRY. [bull. 24| 
The burning- is carried on in vertical kilns, closely resembling lime 
kilns in shape, size, etc. The limestone and fuel are usually fed into 
the kiln in alternate layers, though at a few plants more advanced 
types of kilns are in use. The burned product is crushed and the! 
reduced to powder, commonly in buhrstone mills. Recently advances 
have been made in crushing practice, and several plants now reduce 
their product in tube mills. The manufacturing processes have been 
purposely stated briefly here, because further details concerning them 
will be found in the descriptions of the various natural-cement produc- 
ing districts, which follow. 
XATIIRAL-CEMEISTT RESOURCES OF GEORGIA. 
Two natural cement plants located in northwest Georgia use cement 
rocks from two different geological formations. 
The plant of the Chickamauga Cement Company is located at RossJ 
ville, Ga., a few miles south of Chattanooga. The slaty material used 
is a thin-bedded raw limestone of the Chickamauga (Ordovician) age, 
which is here exposed over a considerable area. In geologic age, M 
well as in chemical composition, this rock is closely similar to the 
cement rock of the Lehigh district of Pennsylvania. The rock is 
quarried and carried up to four vertical sheet-iron kilns of a patented 
(Cummings) design, fired with coal. The burned rock is sent through ! 
a Cummings vertical crusher, and then finally reduced under three 
runs of 42-inch Esopus millstones. 
The product is marketed under the brands of Dixie (natural) and 
New South (" Portland "). It is, of course, all a natural cement, accord- 
ing- to present-day definitions of Portland cement, as it is not artiti- 
cially mixed prior to burning, and the burning is conducted at too low 
a temperature to give a true Portland. That a real Portland cement 
could, however, be readily made from some of this material is proved 
by the following analysis of the burned product. This analysis, by 
Cummings, is quoted from the Twenty-first Annual Report of the 
United States Geological Survey, part (>, page 410: 
Analysis of cement rock from Rossville, do. 
Silica (Si0 2 ) 22. 17 
Alumina (ALA) - 8. j 
Iron oxide (Fe 2 < > 3 ) 2. 50 
Lime ( ( !aO) 65. 68 
Magnesia (MgO) 1. 45 \ 
The Conasauga formation of the Cambrian is described by Dr. C. Wj 
Hayes as "normally composed, at the base, of thin limestones inter- 
bedded with shales, then of yellowish or greenish cla\^ shales, and at 
the top of calcareous shales, grading into blue seamy limestones." 
The Western and Atlantic Railroad, now operated under lease bj 
the Nashville, Chattanooga and St. Louis system, crosses the outcrop 
>P 
