COAL: C AH ABA FIELD. 25 



The northwestern border of the field is made by the escarp- 

 ment of Shades Mountain overlooking Shades Valley; the 

 southeastern boundary is a fault of 10,000 feet displacement, by 

 which the Cambrian strata are brought up to the level of the 

 Coal Measures. Along the southern border of the field from 

 Montevallo westward, this fault has overturned a narrow strip 

 of the measures, including several seams of coal. 



In structure this field is an unsymmetrical synclinal with its 

 axis very close to its southeastern edge. As a consequence most 

 of the strata of the field have a dip to the southeast almost to 

 the edge of the field, the structure seems to be monoclinal, and 

 the greatest thickness of measures is very close to the eastern 

 border. The wider part of the field, to the southwest of the L. 

 & N. Railroad, is divided by an interior faulted anticlinal which 

 separates the Blocton Basin on the west from the Montevallo 

 and other basins on the east. Minor warpings of the strata 

 have broken the field up into a number of smaller basins. 



As with the Warrior Field, so here, the general dip of the 

 field as a whole is to the southwest, and at this end of it we find 

 the greatest thickness of the measures aggregating some 5,500 

 feet, and holding 50 or more coal seams, half of which have in 

 places a thickness of 2. feet and upwards. 



The Maylene basin north of the Montevallo appears to have 

 the topmost measures, and consequently the greatest thickness. 



At the present time mining operations are practically confined 

 to the wider southern end oi the field beyond the line of the L. 

 & N. railroad, the principal center of production being in the 

 vicinity of Blccton, where at least a dozen mines are in active 

 operation, the Thompson seam being the one mainly worked. 

 East of the interior fault and the measures immediately adjac- 

 ent to it, much mining is also done in the Montevallo and May- 

 lene basins on the Montevallo and Maylene seams, and along 

 the Southern Railroad also at Glen Carbon, and near Helena on 

 other seams. 



The mines of the Cahaba field furnished in 1903 1,781,078 

 ions of coal. This coal was mined from eight different seams 

 ai d nineteen mines, eighteen of which were slopes, and one a 

 drift. 



As a general rule, the Cahaba coals are of excellent quality. 

 Some of them are the finest steam and domestic coals in the 

 state, and from some an excellent quality of coke is made. The 



