CAHABA COAL FIELD : GENERAL DESCRIPTION. 9 
scribed, viz: Rocky Ridgq, Blackjack Ridge, and Grassy 
Ridge, and lying to the southeast of the last named and 
parallel with it, is Owen’s Mountain, formed of the sand- 
stones and slates overlying the Nunally seam. This moun- 
tain is not continuous through the field like the others, but 
in the northern part it is quite as high and prominent as 
the Millstone Grit ridges. 
Besides the mountains above mentioned, which are 
formed of the rocks of the Coal Measures of the Cahaba 
Field, there are a few others lying outside the limits of this 
field, which deserve mention here as affording prominent 
and important land-marks to guide the explorer in his ex- 
aminations of the Cahaba Field. 
There are two very prominent mountains to the south- 
east of the Cahaba Coal Field ; the first one is a high and 
continuous cherty ridge running within half or three-quar- 
ters of a mile of the Coal field, along its southeast side, 
with "Possum Valley between it and the Coal field. This 
ridge, formed of the chert of the Silurian formation, bears 
the name of New Hope Mountain in Shelby County, Mill 
Ridge in Jefferson County, and in St. Clair County it is 
known by the name of Pine Ridge, changing to Anderson 
Mountain at the north end. Beyond this to the southeast 
is a higher mountain than any yet mentioned—the highest 
in sight of the Cahaba Coal Field. This mountain is known 
in Shelby and Jefferson Counties by the name of Big Oak 
Mountain ; in St. Clair County some of the settlers call it 
the Coosa Mountain; about three miles above Carr’s Gap, 
where the Georgia Pacific passes through it, this mountain 
acquires an altitude exceeding anything in the neighborhood 
of the Cahaba Coal Field. This high part of the mountain 
bears the name of “ Bald Rock.” Big Oak Mountain is 
formed of the Millstone Grit of the Coosa Coal Field. 
On the northwest side of the Cahaba Coal Field and on 
the opposite side of Shades Valley is the Red Mountain 
that contains the thick stratified vein of red fossilliferous 
iron ore, from which the Birmingham furnaces are mostly 
supplied. This mountain is a prominent land mark along 
the northwest side of this Coal Field nearly its whole 
length ; its distance from the top of Shades Mountain varies 
