NORTH CAROLINA. 



477 



4 



Igneous. In the direction of this notion certainly point, the absence of strati- 

 fication, the non-occurrence of limestone, and the great predominance of 

 syenytes (mostly hyposyenyte), and other iron-bearing and basic rocks. I 

 have only placed them as the lower Laurentian, hovyever, since there seems to 

 be a general disinclination to suppose that the primal igneous core anywhere 

 shows itsOlf to human inspection. This belt may well be characterized as the 

 geological axis of the State. The group of rocks just described is bounded on 

 the northwest by a series of gneisses and feldspathic and occasionally horn- 

 blendic slates, which extend westward with little interruption to the Blue 

 Eidge, and, except a narrow zone of a few miles breadth along the course of tliat 

 chain, includes the whole mountain region to the flanks of the Smoky Moun- 

 tains, through the greater part of its length. These are considered to belong 



to the Laurentian proper A few miles west of this is a narrow terrane 



of syenytes and other hornblendic rocks and granites The2:)redominance 



of hornblendic rocks, the absence of mica, and the general absence of stratifica- 

 tion have seemed to justify the reference of this belt to the lower part of the 



series, along with the preceding central zone Another considerable 



area of Laurentian rocks is found beyond the Blue Ridge, occupying most of 

 the mountain plateau between that and the Smoky Mountains, and in places 

 constituting the materials of these chains. As stated before, this area may 

 very properly be considered as only a continuation of the preceding, from 

 which it is divided by a very narrow and interrupted belt of Huronian slates. 

 .... The rocks of both of these, like those of the preceding area, are foliated 

 for the most part, and consist of indefinite alterations of the same kinds of 

 mctamorphic strata, — gneiss, iKjrnblendic, feldspathic and micaceous schists, 

 and occasionally chloritic and talcose slates." 



In regard to the principal Huronian belt, Professor Kerr makes tho 

 following statement (/. c, p. 133) : 



" The belt is bounded on both sides by the Laurentian, already described, on 

 w^hich it lies unconformably, and from which its materials were derived. The 

 stratigraphy therefore indicates the horizon of these rocks to be the Huronian, 

 and the lithology agrees well with that determination ; and the reasonable 

 course therefore seems to be, to place them as Huronian, until some evidence 

 shall be found of an organic character, to lift them to a higher geological 

 plane. Tlie absence, or at least the non-discovery of fossils hitherto, in an 

 extensive body of slates like those of the middle and west portions of this 

 tract, so little altered and so wejl adapted to the preservation of even the most 

 delicate organisms, and in a region so much studied, and on account of numer- 

 ous mines, offering so good opportunities for the discovery of fossils if any 

 existed, is certainly so far confirmatory of the sub-Silurian theory of these 

 deposits. This is the principal area of Emmons' Taconic in this State." 



Prof. F. H. Bradley, however, who had made a special study of the 

 rocks of Eastern Tennessee, subsequently e,xamined a considerable por- 



