XIII. ] GEOGNOSY OF THE APPALACHIANS. 275 



schists of the second and third series were regarded as altered 

 primal rocks by H. D. Rogers, others, lithologically similar, 

 were referred by him to the older so-called azoic series, which 

 we believe to be their true position. Professor "W. B. Rogers 

 has lately informed me that in Virginia a gneissic series, having 

 the characters of the Green Mountain rocks, is clearly overlaid 

 unconformably by the lowest primal palaeozoic strata of the 

 region. Coming northward, the uncrystalline argillites and 

 sandstones holding Paradoxides, at Braintree, Massachusetts,* 

 and St. John, New Brunswick, overlie unconformably crystal- 

 line schists of the second series ; and in the latter region, in 

 one locality, rocks which are by Bailey and Matthew regarded 

 of Laurentian age. In Newfoundland, in like manner, a great 

 series of crystalline schists, in which Mr. Murray recognizes the 

 Huronian system as first studied and described by him in the 

 West, is unconformably overlaid by a group of sandstones, lime- 

 stones, and slates, holding Paradoxides. The peculiar gneisses 

 and mica-schists of the White Mountain series appear to be 

 developed to a great extent in Newfoundland, which led me to 

 propose for them the name of the Terranovan system, t 



From the part which the ruins of these rocks play in the 

 production of succeeding sediments, it is not always easy to 

 define the limits between the ancient mica-schists and the 

 Cambrian strata in these northeastern regions. It is not im- 

 possible that the two may graduate into each other, as some 

 have supposed, in Newfoundland and Nova Scotia ; but until 

 further light is thrown upon the subject, I am disposed to re- 

 gard the relation between the two as one of derivation rather 

 than of passage. 



We have already alluded to the history of the rocks of the 

 White Mountains, formerly looked upon as primary, and by 

 Jackson described as an old granitic and gneissic axis uplifting 

 the more recent Green Mountain rocks. Their manifest differ- 

 ences from the more ancient gneiss of the Adirondacks, and 

 their apparent superposition to the Green Mountain series, then 



* Hunt, Proc. Bost. Soc. Nat. Hist., October 19, 1870. 

 t American Journal of Science (2), L. 87. 



