ott.] GEORGIA TERRANE. 101 



formerly referred to the Hudson River are considered to belong to the 

 Primordial fauna. 1 



The geologists of the Vermont survey iu their final report included 

 the shales and associated slates and arenaceous beds under the title of 

 Georgia group. In proposing the name Georgia group to designate 

 these rocks, Prof. 0. H. Hitchcock said : 2 



We use the term Georgia group to designate this terrain, from the town of Georgia 

 in Franklin County, where it is developed in its full proportions and where the most 

 interesting fossils have been found. It is a name also which does not involve any 

 theory, and may be used by both parties iu the controversy respecting its age. * * * 

 The Georgia slate includes what Prof. Emmons has ranked as the black slate, Ta- 

 conic slate, and roofing slate; and yet not altogether, for we have regarded all the 

 black slate beneath the red sandrock as belonging to the Hudson River group. The 

 characteristic trilobites of the Georgia slate are represented by Emmons in his Ta- 

 conic System, 1844, as found in the black slate. 



The following fossils are cited as characterizing the Georgia slate in 

 Vermont: Barrandia thompsoni Hall, B. vermontana Hall, Bathynotus 

 holopyga Hall, Graptolithus milesi Hall, the trail of an annelid, and 

 unknown species of fucoides. 3 



The stratigraphic position of the Georgia series was considered to be 

 above the sandstone which represented the Oneida conglomerate, and 

 the thickness of the slate was thought to be at least 3,000 feet. 4 A 

 discussion of the stratigraphic position of the faunas found in the 

 Georgia slates by Prof. James Hall, Sir William E. Logan, and M. J. 

 Barrande, accompanies the chapter. A fair presentation of the argu- 

 ment for and against the Silurian age of the terrane is given. In a 

 note upon the trilobites of the shales of the Hudson Eiver group, iu 

 the same volume, Prof. Hall redescribes the fossils mentioned in his 

 paper of 1859. In the second volume of the Geology of Vermont, on 

 page 799, the u sparry limestones" occurring as thin bands in the roof- 

 ing slate series in Fairhaven, Vermont, are correlated with the red sand- 

 rock or Wiuooski marble of the uorthern portion of the State. 



In describing the rocks of Waterville, Maine, Prof. O. H. Hitchcock 5 

 states that the slates are similar in mi nera logical structure to the 

 Georgia slates of Vermont, which* are equivalent to the Potsdam sand- 

 stone. 



With the determination (a) by Mr. E. Billings that the " Red sand- 

 rock" was of primordial age; 6 (b) by Mons. Barrande that the fossils 

 from the Georgia slate belonged to the Primordial fauna; {c) that the 

 u Granular Quartz" was the basal member of the Paleozoic, and had 

 been correlated with the Potsdam sandstone, which, from its included 



'Op. cit, p. 732. 



'Hypozoic and Paleozoic rocks. Keport od the geology of Vermont, vol. 1, 1861, p. 358. 



• Op. cit., p. 367. « Op. cit. , p. 366. 



• General report on the geology of Maine. Preliminary Rep. on the Nat. Hist, and Geology of Maine. 

 Augusta, 1861, p. 233. 



• On the age of the red sandstone formation of Vermont. Am. Jour. Sci., 2d aer., vol. 32, 1861, p. 232. 



