478 



THE AZOIC SYSTEM AND ITS SUBDIVISIONS. 



tion of Western North Carolina, as well aa the adjacent regions of 

 Georgia and Alabama. In a series of papers entitled " On the Silurian 

 Age of the Southern Appalachians," (Amer. Jour. Sci., 1875, (3) IX., 

 pp. 279-288, 370-383,) this geologist reaches conclusions which he thus 



states : — 



" The rocks of that po-*ion of North Carolina south and west of the Little 

 Tennessee, together with the metainorphic area of Georgia, north of a lijie par- 

 allel with and ten miles south of the Chattahoochee (and probably that south of 

 this line), and the entire metamorpbic area of Alabama, are Silurian or newer, 

 with the possible exception of two or three small patches not over ten miles in 

 diameter." (I. c, p. 280.) 



Professor Kerr acknowledges that, if Professor Bradley's identifications 



prove valid, it will probably be found that all the Hnronian rocks except 



those of the middle and eastern belts will prove to be Silurian. Of 



these he remarks (I. c, p. 140) : 



*' .But this conclusion will not involve the groat middle and eastern belts 

 which must still remain Hnronian, until determined independently to belong 

 to a later scries ; both because they are widely separated from the others, and 

 because they have lithological and stratigraphical characters of their own, which 

 would prevent their following any rleterminations of horizon for the others, 

 ■which should be based on these considerations alone." 



In regard to an area adjacent to Tennessee, Professor Kerr says (/. c.j 

 p. 139):- 



*' This belt of rocks is colored on the map throu^.iout hke the other Huro- 

 nian belts, and for the same reasons, viz. : that they succeed the Laureutian, 

 and differ from them strongly in degree of metamorphism and general litho- 

 logical character, so that the transition from one to the other is obvious along 

 the whole extended line of contact, and that they have yiekled no fossils, 

 which alone could authorize their reference to a later age. And although the 

 fact of unconformability can not be asserted for any one of the sections, this may 

 arise from the circumstance that the disturbance and dislocation of the strata 

 along this line are extreme, and tliat no detailed or minute examination has 

 ever been attempted, and of course nothing short of such examination wouhl 

 suffice in such a region. And another circumstance of weight is the immense 

 body of these rocks, which nnist be allowed, on the French Broad for example, 

 after every reasonabk*, reduction for folding, a thickness of several miles. Add 

 these to the primordial or the lowest members of the Lower Silurian, and they 

 receive a most incredible development downwards, since the rocks along the 

 Tennessee border referred to this h(jrizon have already a very great thickness. 

 However, as stated above, these rocks have ordy been located provisionally. 

 And it is right to say further that the only examination T have made of this 

 western Smoky belt, was a mere reconnoisance, mostly on horseback, made in 

 a few weeks in the autumn of 180G." 



