146 CEMENT MATERIALS AND INDUSTRY. [bull. 1243. 
HUNTON LIMESTONES. 
Separated from the Viola limestone by about 150 to 300 feet of clay 
shale is a Silurian formation having an average thickness of about 200 
feet. This formation varies in physical character and in composition 
through its section. A massive bed at the base is in places almost 
pure limestone and is white, while in others it is in large part silici- 
fied. In the central part beds of clay and marl are interstratitied 
with the limestone. Samples of limestone from the lower part of 
these beds contain a small amount of magnesia. Toward the top the 
limestone is white to light yellow and becomes more massive. Some 
of the layers near the top, however, contain local segregations of 
chert. In the reports above cited this formation is known as the Hun- 
ton limestone. Like the Viola limestone, it outcrops around the bor-i 
ders of Arbuckle Mountains in a narrow belt, besides occurring in 
many small areas in the central part. 
CARBONIFEROUS LIMESTONES. 
In northern Indian Territory are a few belts of Carboniferous lime 
stones — continuations of the areas which are so important in Kansas 
These limestones thin out and disappear to the south, however, and 
are probably of Workable thickness only in the Cherokee Nation. 
Other formations of middle Carboniferous age occur in the eastern 
part of the Cherokee Nation and extend into Arkansas north of the 
Boston Mountains. These limestones are thin bedded, and with them 
are associated deposits of blue to black clay shales. Analyses of some 
of the beds from their eastern extension in Arkansas show only a trace 
or a fraction of a per cent of magnesia. 
In central Choctaw Nation and along the southern edge of the coal 
field, is a long lentil of Carboniferous limestone of the same age and 
character as the limestones in eastern Cherokee Nation. In the cen 
tral part of the exposure many of the beds are massive and the forma- 
tion attains a thickness of nearly 300 feet. The eastern end of these 
exposures extends nearly to the Arkansas line on the north flank of 
the Ouachita Mountains, while the west end is in the edge of the 
Chickasaw Nation, against the Arbuckle Mountains. Judging from 
physical characters this limestone is essentially the same in quality as I 
limestones above described in eastern Indian Territory and Northern 
Arkansas. 
CRETACEOUS LIMESTONES. 
Cretaceous limestones occur in the southern part of the Territory, 
in several distinct formations associated with the limy clays. These 
limestones are mostly soft, thin bedded, and are of various shades, 
