VALLEY REGION DETAILS; SHADES VALLEY. 173 
two, and by this a synclinal is also formed in the Red 
Mountain strata. The Red Mountain has everywhere along 
its eastern flank a covering of the chert of the Sub-Carboni- 
ferous, and the Black Shale, which comes between the Clin- 
ton and the Sub-Carboniferous, while not always to be seen 
on account of its being very thin and easily eroded, is no 
doubt present in the majority of cases. On the western 
face of the Red Mountain, the Trenton limestone may al- 
ways be seen, sometimes near the base of the mountain, 
sometimes nearer the top, according to locality, and this 
rock is extensively quarried, notably at Gate City, where 
the limestone extends up to the very top of the mountain, 
and the Clinton strata are all on the eastern flank of the 
same. This varying position of the Trenton is due to local 
causes, among which the occurrence of undulations running 
across the valley is perhaps the most effective. 
Next to the Red Mountain with its constituent formations, 
follows the Knox Dolomite, making first a belt of ridgy 
lands, seen in the South Highlands, and then the redlands 
with their gentle undulations and characteristic soils, as 
may be seen near Elyton and in some parts of the city of 
Birmingham itself. It is rarely that the strata of the Knox 
Dolomite appear in their original form so that their dip 
may be clearly recognized. Usually the formation is 
represented by great accumulations of loose fragments 
of chert, or by the red loams in which bedded rocks 
are rarely found. Loose angular fragments of chert 
imbedded in the red soil are however very common and 
characteristic. This eastermost belt of the Knox Dolomite 
rocks presents no special features. Inthe lower part of the 
map it is in great measure covered by the Tuscaloosa sands 
and clays, though cropping out in spots over a pretty wide 
area here. On account of the covering of these surface 
materials it has thus far been impossible to make out with 
certainty the structure of all this lower part of the map. 
In the upper part of the region covered by the map, we 
find a second wide and apparently continuous outcropping 
of the Knox Dolomite, I mean above Eastlake, up to the 
end of the Blount Mountain. This is due, as may have al- 
ready been inferred by the reader of the preceding para- 
