CALIFORNIA GEORGIA. 
59 
Transportation and market. — The Eldorado County slates have practically no com- 
petition on or near the Pacific coast, while the Eureka quarry has recently placed 
large shipments in Hawaii and Guam. Until recently the principal problem has 
been the transportation of the slates from the quarry to the railroad. This was 
formerly done by wagon hauling over a 6-mile stretch of very hilly road. Dining 
the last season, however, the Eureka Slate Company has installed an aerial tramway 
system from its quarry to a point near Placerville. This tramway is an engineering 
feat of no mean order, the crossing of the South Fork of American River being the 
principal difficulty encountered. 
Production of roofing slate in California. — The following table, compiled from figures 
given in various volumes of Mineral Resources of the United States, shows the amount 
and value of California slate production for a number of years: 
California production of roofing slate, 1890-1901. 
Year. 
Quantity. 
Value. 
Year. 
Quantity. 
Value. 
1890 
Squares. 
3,104 
4,000 
3, 500 
$18, 089 
24,000 
21,000 
1896 .. 
Squares. 
4,597 
1 , 000 
400 
928 
3, 500 
2, 500 
$20, 388 
7 000 
1891 
1S97 
1892 
1898 .. 
2 700 
1893 
1899 
6,642 
1894 
900 
I, 500 
5, 850 
10, 500 
1900 
26 500 
1895 
1901 
IS, (108 
GEORGIA. 
By Edwin C. Eckel. 
The workable roofing slate deposits of Georgia occur in the Rockmart (Ordovician) 
formation, and are developed only near the town of Rockmart, Polk County. 
Geology of the slates. — In a recent publication" of this Survey, Dr. C. W. Hayes has 
described the geologic relations of the Georgia slates as follows : 
The Rockmart formation is confined to the Cedartown and Rockmart areas, in the southern portion 
of the Rome quadrangle. As stated previously, these rocks are contemporaneous with the upper 
portion of the Chickamauga limestone north of the Coosa Valley. The formation consists chiefly of 
black slates, originally calcareous shales, but sufficiently altered for the development of slaty 
cleavage. In addition to the slate, which occupies the lower portion of the formation, it contains 
beds of highly ferruginous sandstone and some cherty limestone. It also contains coarse conglomer- 
ates, made upof limestone pebbles embedded in an earthy matrix. This upper portion of the forma- 
tion was evidently deposited near the margin of the sea, where the supply of sediment was abundant 
and variable in character. 
The most extensive slate quarries in the United States south of Pennsylvania are located at Rock- 
mart. The formation in which the quarries are located, the Rockmart slate, extends across the 
border into the Rome quadrangle, but it is not certain that any workable slate will be found in this 
area. The formation is variable in composition, and to the north of Rockmart consists largely of 
unaltered clay shales with beds of ferruginous limestone and sandstone, 
The portion of the formation which now produces roofing slate was originally a fine-grained homo- 
geneous clay shale. Under the influence of metamorphism, connected probably with the extensive 
faulting which the region has undergone, a very perfect slaty cleavage was developed, which gen- 
erally obscures, and in some cases entirely obliterates, the original bedding. East of the quadrangle, 
along the Cartersville fault, the slate is generally wrinkled near the fault, so that it does not cleave 
readily, and at a considerable distance from the fault the cleavage is only imperfectly deveh ped. 
Hence the best slate will be found within a comparatively narrow belt, from 1 to 5 miles from the 
fault. 
a Hayes C. W. 
Survey, 1902. 
Description of the Rome quadrangle: Geologic Atlas U. S., folio 78, U. S. Geol. 
