172 GEOLOGICAL SURVEY OF ALABAMA. 
viz., the Oxmoor shales and sandstones, lying between the 
edge of the Cahaba Field and the East Red Mountain. 
This valley is in great part drained by Shades Creek and is 
known as Shades Valley. Its abnormal width is due to the 
undulations in the strata, since the Sub-Carboniferous beds 
are no thicker here than in other parts of this valley where 
the width is much less. These undulations are accompanied 
by faults in some parts of Shades Valley, as for instance be- 
tween Oxmoor and Grace’s Gap, but these displacements 
have not yet been traced out with sufficient detail to permit 
of their being properly mapped. 
Shades Valley is diversified by long ridges formed by the 
sandstones of the formation, and it is usual to find a very 
distinct and persistent ridge near the western edge of the 
valley formed by sandstones that occur near the base of the 
formation. Limestones occur in these shales, as has been 
already noted, and in one place near Oxmoor this rock has 
been quarried. 
The next following topographic feature to the northwest 
of Shades Valley, and by far the most important one in the 
region, from an economic standpoint, is the Red Mountain. 
In the lower part of the area shown on the map, i. e., below 
the crossing of the Cahaba Coal Company’s railroad, the 
Red Mountain does not form a conspicuous topographic 
featuregas it is rather low and in many places covered by 
the sands and other beds of the Tuscaloosa formation. 
Above the point named, it begins to assume, at least in 
places, tle _ ae of a mountain, and so it continues 
with constantly incréasing height and importance almost to 
the upper limit of the map. I shall not attempt here to 
speak in detail of the variations observed in the strata of 
Red Mountain, nor to give sections across it, since the re- 
port of Mr. McCalley, soon to be published, will fully treat 
of this part of the subject. Most of the mines at present in 
operation in the Red Mountain are found between Spark’s 
Gap and Trussville, the greatest thickness of ore, about 
twenty feet, being about the middle part of this stretch of 
the mountain. Above Gate City, Red Mountain turns some- 
what away from the edge of the Cahaba Field, and the re- 
versed anticlinal above spoken of, comes in between the 
