VALLEY REGION; OHARACTERS OF THE ROCKS. . 149 
tough and hard, and, especially towards the east, assume 
gradually the characters of the semi-crystalline rocks, and 
it is capable of demonstration that some of the partly 
crystalline slates of the eastern part of the Coosa Valley 
are only the changed or metamorphosed representatives of 
this division, which has been called the Montevallo or 
Choccolocco Shales from the characteristic occurrences in 
those localities. In Jones’ and Cahaba Valleys these do 
not play a very important part except in the lower part of 
the Cahaba Valley from Centerville up to Montevallo. Be- 
yond this limit they outcrop only in narrow and compara- 
tively unimportant belts. In the upper part of the Monte- 
vallo Shales we find beds of blue limestone and gray 
dolomite which are often difficult to distinguish from similar 
rocks occurring in the next overlying formation. In fact 
the line between the Shales and the Knox Dolomite is, so 
far as Alabama is concerned, rather an arbitrary one. 
Weisner Quartzite-—In the Shales above described and most 
commonly in their lower parts, are found in the eastern part 
of the Coosa Valley great beds of quartzite and conglomerate 
many hundred feet in thickness, but often of very limited 
extent geographically. The quartzites always form high 
and rugged mountains sometimes stretching for miles in an 
unbroken range, but as often forming detached and isolated 
peaks, rising suddenly out of the plains and as suddenly 
sinking down to the same level. The “Mountain” near 
Columbiana, the Kahatchee Hills, Alpine Mountain, Mount 
Parnassus at Talladega, Cold Water Mountain and Blue 
Mountain near Anniston, Ladiga Mountain above Jackson- 
ville, Weisner Mountain east of Jacksonville, are instances 
of occurrences of this quartzite. The Weisner Mountain 
above named has been best studied, and its stratigraphical 
relations to the Coosa Shales and to the Choccolocco 
Shales, most clearly made out, for which reason we have 
used the name Weisner Quartzite to designate this member 
of our Cambrian, which occurs interpolated in the Shales as 
local masses of lenticular shape and often of very great 
thickness. 
Prof. Safford, of Tennessee, has given the name Chilhowee 
to similar great masses of sandstone and quartzite occurring 
