wat.cott.] GEORGIA TERRANE. 103 



Wlieu tracing the formations that occur north of the Vermont and Can- 

 ada boundary to the southward, Sir William E. Logan studied a section 

 in the vicinity of Swanton, Vermont, in which the Georgia slates and the 

 Olenellus fauna occur above the Eed sandrock. 1 The latter are red and 

 white dolomites in sandy layers. The measurement of this section gave 

 a thickness of 710 feet, including 190 feet of shale, carrying the fossils 

 which Mr. Billings described. He traced the rocks of the Swan ton sec- 

 tion north to the vicinity of Saxe's Mill, near the United States and Cana- 

 dian border, where a measured section of the dolomitic sandstone gave 

 a thickness of 1,410 feet. 2 These sections cross the Red sandrock forma- 

 tion of the older authors. The name Eed sandrock is a misnomer, as 

 there is in reality comparatively little sand or arenaceous material, other 

 than arenaceous limestone of a highly dolomitic character, in the entire 

 section. 



Prof. Jules Marcou took a very active interest in the discussion of 

 the strati graphic position of the fauna found in the slates of Georgia, 

 Vermont, and published numerous papers upon the subject from 18C0 

 to 1888. In a paper published in 1861 3 he records some of his own 

 observations, saying that in Vermont the Potsdam sandstone has ex- 

 actly the same aspect and composition as at Potsdam, in the State of 

 New York. Near Saxe's Mills, a mile east of Highgate Springs, it con- 

 tains two species of Conocephalites, G. adamsi and C. valcanus. He 

 states that the formation is broken up into narrow bands that are 

 numerous and well developed west of Mr. Parker's farm at Georgia, 

 and also on the road between St. Albans and Swanton, Vermont; and 

 that although at first they appear to be interstratified with the Georgia 

 slates, they are not so, but may be compared with the steps of a ladder 

 placed over, or even a little wedged into the Georgia slates and Lingula 

 flags. He says: 



This group has been known for a long time in Vermont by the name of Red Sand- 

 rock. * *" * Below the Potsdam sandstone lie great masses of slate, four or five 

 thousand feet thick, which for convenience I should divide into three parts. 4 



These are the Lingula flags, Georgia slates, and St. Albans group. 



The Georgia slates are stated to be characterized by Primordial fos- 

 sils, notably Paradoxides (Olenellus) thompsoni, P. vermontana, Peltura 

 holopygci) Obolella cingulata,- etc. 5 



In noting the discovery of fossils in the Winooski marble, at Swanton) 

 Vermont, Mr. E. Billings 6 states that fossils were discovered by Mr. 

 Solon M. Allis, of Burlington, Vermont, who sent them to him for ex- 



1 Geological Survey of Canada; report of progress from its commencement to 1863. Montreal, 1863, 

 pp. 281, 282. 



2 Op.cit.,p. 282. 



s The Taconic and Lower Silurian rocks of Vermont and Canada. Boston Soc. Nat. Hist. Proc, vol. 

 8, 1862, pp. 239-253. 



4 Op. cit., p. 244. s Op. cit, p. 245. 



'Note on the discovery of fossils in the " Winooski marble," at Swanton, Vermont. Am. Jour. Soi., 

 3d ser., voL 3, 1872, pp. 145, 146. Canadian Nat., new ser., vol. 6, p. 351. 



