VALLEY REGION DETAILS ; COOSA COAL FIELD. 169 
Mill on Shoal Creek, there is one of the most interesting 
sections known to me. Here may be seen a bed of coal 
three or four feet in thickness, i in nearly horizontal position, 
with the shaly limestones of the Montevallo series resting 
directly uponit. The accomyanying view from a photograph 
shows this very clearly. Mr. Squire has shown that the 
Coal Measures along this part of the field have been over- 
turned, and the bottom fireclay is in every case on top of 
the seam. In the faulting, therefore, not only has a large 
strip of the Coal Measures been pushed over, but the Cam- 
brian strata have been slipped up and over these reversed 
beds. 
The map does not show very clearly the manner in 
which the Cambrian passes around the apex of this angle 
of Coal Measures, for in reality these older measures seem 
to lap up upon the angle of the Coal Field in a series of great 
parallel waves like breakers upon an exposed point of the 
shore. These waves do not accommodate themselves to 
the turn in the boundary of the Coal Field by bending 
round, as might be inferred from the arrangement of the 
colors on the map, but they keep their original direction, 
(northeast and southwest), on the two sides of the salient 
angle, just as waves pass an obstruction. 
All along the Cahaba Valley and its extension soutiggard 
and southwestward of Montevallo, the area nal 
Knox Dolomite is characterized by | the occurrence . of; beds 
of brown iron ore or limonite that fn many placeg ae des- 
tined to be af great economic value. Oy } 
For lack of means of transportation, only one furnace has 
up to the present time been built to utilize these ores. 
Coosa Coa FIELD. 
The structure of the Coosa Coal Field does not at this 
time particularly concern us, but the portion of it included 
in the map shows that itis divided into two parts by a fault 
which brings up some of the Sub-Carboniferous shales be- 
tween the two. This belt of shales’ varies in width from 
half a mile upwards, and the amount of displacement is not 
very. great, since it extends only from the lower part of the 
shales up to the Millstone grit. Mr. McCalley’s report will 
give a tolerably full. account of the structure of this field. 
