64 GEOLOGICAL SURVEY OF ALABAMA. 
Millstone Grit, and one of its peculiar features is its assum- 
ing a more red or pinkish tinge than the layers of Shades 
mountain and Pine ridge ; it has the same peculiarity in the 
Warrior Field, which can be noticed along the South and 
North Alabama Railroad, south of Reid’s Gap. Above the 
Millstone Grit of Chestnut ridge, and both above and below 
the Nunnally seam, most of the sandstones have a pinkish 
tinge at their outcrops ; this is a characteristic of this part 
of the measures. After passing over two hundred feet of 
measures above the Harkness seam, you will arrive at the 
lower edges of another great landmark and characteristic 
rock, the one hundred foot ledge of the blue micaceous 
sandstone ; a close examination of this ledge will aid you in 
apy investigation of the same series of measures in other 
parts of the Cahaba Coal Field, (also in Warrior and Coosa 
Coal Fields.) Passing over this hundred foot ledge, you 
will find that the sandstones above it are more micaceous 
than they are below it; these overlying sandstones acquire 
a new feature which attaches to most of the ledges immedi- 
ately below and above the Wadsworth seam—that is, their 
becoming concretionary, and resembling, when broken the 
layers or skins of a halved onion ; but the great guide to the 
identification of the seams in this part of the coal measures, 
is the large ledge just mentioned of blue micaceous sand- 
stone. The guide to the identification of the Wadsworth 
seam is the two to six inch ledge of pale blue or green 
block sandstone, which underlies the Wadsworth at a varying 
distance of from forty to ninety feet. Leaving the Wads- 
worth seam and continuing southeast, after passing over 
one hundred feet of measures, you will find a sandstone 
toat is remarkably concretionary in places, but immediately 
above the Wadsworth is a coarse sandstone that shows very 
red at the surface. Ascending in the measures to a point 
one hundred and twenty feet above the Wadsworth seam 
you will arrive at a hard micaceous grey sandstone con- 
taining a thin ten inch seam ; at one hundred and seventy- 
five feet above the Wadsworth is another thin seam of 
about twelve inches; about two hundred feet above the 
Wadsworth is a fossiliferous grey sandstone; about two 
hundred and fifty feet above the Wadsworth is a massive 
