14 GEOLOGICAL SURVEY OF ALABAMA. 
In the vertical sectious represented on the accompanying 
map, the Henry llen Vertical Section shows the relative posi- 
tion of the seams anda rocks in the Henryellen Basin. The 
South and North Alabama Railroad Vertical Section shows 
the seams and rocks of the Cahaba Basin, the Helena Basin 
and the measures of the adjacent territory. The Dailey 
Creek Vertical Section shows the seams and rocks that cut- 
crop in that basin between the interior fault and the Stine 
seam outcrop. The Blocton Vertical Section shows a sec- 
tion of the measures that have so far been explored. There 
are undoubtedly other seams in the part marked unexplored, 
that the drill or future explorations will bring to light. 
The General Vertical S ction shows the combined informa- 
tion gathered from all parts of this Coal field. 
The rocks or Coal Measures of the Cahaba Coal Field 
have an aggregate thickness of 5,525 feet. For the conven- 
ience of miners, exploring students, and others, I have 
classified these measures into four groups : 
(1.) The first or lowest group extends from the base of 
the Millstone Grit to the top of it, or in other words, to the 
top of the “shield rock” of Chestnut Ridge or Grassy 
Ridge, between the Gould outcrop and the Nunnally seam 
outcrop ; I have named this one the “Jfillstone Grit Group.” 
(2.) The next group above the Millstone Grit Group, ex- 
tends from the top of the Millstone Grit to the top of the 
hundred feet of blue micaceous sandstone; I have named 
this group the “Micaceous Group”. (There are about 200: 
feet in thickness of measures between the top of the hund- 
red feet of blue micaceous sandstone and the Wadsworth 
seam.) 
(3.) The group above this extends from the top of the 
hundred feet of blue micaceous sandstone to the Monte- 
vallo seam ; I have named this one the “Productive Group.” 
(4.) The fourth or topmost group extends from the 
Montevallo seam to the top of the measures, (about 500: 
feet); I have named this one the “Conglomerate Group.” 
The rocks forming the dividing line between these groups 
are good landmarks all over this coal field, wherever they 
are exposed. 
These four groups are all tinted differently on the accom- 
