20 GEOLOGICAL SUBVEY OF ALABAMA. 



THE SECOND CONGLOMEKATE. 



This is the rock so often referred to in Prof. McCalley's 

 report on the "PLATEAU EEGION or ALABAMA" and elsewhere, 

 as the "Upper Conglomerate." It is truly designated there 

 as the "upper," because it is so in fact, there being no other 

 conglomerate above it. It is there generally the top rock of 

 the series. But in this field it lies comparatively near the 

 base of the productive coal measures. Probably the greatest 

 horizontal distance between the top of the First Con- 

 glomerate, and the base of the Second, is 3050 feet, while 

 the thickness of strata intervening is 336 feet. These figures 

 are probably too high for a general average of thickness of 

 strata, or distance between these rocks ; but they were ob- 

 tained at the only place found where measurements could be 

 made with approximate accuracy ; and are fairly represen- 

 tative for a large portion of this field. 



This rock resembles the First Conglomerate in many 

 respects, and general structure, yet differs from it so much 

 in general appearance, that the one need never be mistaken 

 for the other. Its pebbles are generally smaller, less crys- 

 talline, and less firmly cemented together, and where peb- 

 bles are wanting the rock is generally of a lighter grey color, 

 and of more coarse quartzitic structure than the other. It 

 is also in the region under consideration, much more mas- 

 sive and prominent than the First Conglomerate, often rising 

 up very boldly above the surface wdth its outcrop covering a 

 space of from a quarter to three quarters of a mile wide. 

 That the thickness varies greatly is evident, but at no place 

 has it been found possible to measure it, except by the space 

 it occupies. 



In the lower, or southwest end of the field, it comes near 

 to the surface over a wide space, making all that portion 

 drained into Canoe Creek, a plateau region. Its southeastern 

 outcrop makes the ridge known as Buck Ridge from Fall 

 Branch in T. 14, E. 1 E., and running thence north eastwardly 

 through that Tp, and T. 14, E. .2 E., and T. 13, E. 3 E. It 



