158 GEOLOGICAL SURVEY OF ALABAMA. 
formations is often very much hindered by the fact that they 
are more or less completely covered by superficial beds of 
sand and clay which have been spread over them after they 
had through the agencies above spoken of, been carved into 
topographic forms substantially the same as they now ex- 
hibit. The materials of this later formation are often dis- 
tinguished by a purple or dark red color, the sands are 
mostly yellow, and show lines of cross-bedding, the gravels 
are unevenly distributed, and much less abundant than the 
sands. The clays as well as the sands with which they are in- 
ter stratified, are more particularly characterized by the pur- 
ple color mentioned, but there are many beds of the clay that 
are light gray and white. In a few places these clays are 
utilized for making refractory bricks, and the better grades 
of pottery, as at Woodstock, Bibbville, and Tuscaloosa. 
With careful selection and manipulation, there is hardly - 
doubt that these clays will be found suitable for all the uses 
to which the New Jersey clays are put, since they are es- 
sentially similar and belong to the very same geological 
formation. The formation contains a good deal of iron, 
which appears in the form of sandy and aluminous ores 
with 25 to 35 per cent. of metallic iron, usually scattered 
over the summits and along the slopes of the low hills of 
this region. The per cent. of iron is as a rule too low, and 
that of the silica too high to permit of these ores being 
used while we have such an abundance of ores of better 
grade. 
POST TERTIARY.—-Over the greater part of the State, 
except perhaps the extreme northeast, we find surface beds 
of very similar materials to those just described overlying 
the older formations. From about the limits marked on the 
map for the Tuscaloosa beds to the extreme border of the 
State towards the southwestward, we find these later beds 
occupying the surface, often to the extent of completely 
hiding the older rocks below, and forming the great bulk of 
the cultivated soils from the latitude of Tuscaloosa down. 
The distribution of these later beds within the limits of 
this map may be considered the same as that shown for the 
Tuscaloosa, and indeed where one is present the other is 
also in most cases, the Tuscaloosa below, the Orange Sand, 
