OCCUiillENCE OF FOSSILS 227 



Belt terrane of Montana, and the Etcheminian terrane of New Bruns- 

 wick and Newfoundland, if the latter proves to be truly pre- Cambrian. 



REVIEW OF EVIDENCE CONCERNING FOSSILIFEROUS CHARACTER OF CERTAIN 



PRE- CA MBRIA N S TRA TA 



Fossils from the Algonkian. — The reported discoveries of fossils in the 

 crystalline rocks of the Algonkian are as yet too problematical to be of 

 value to the geologist and paleontologist. Apparently the best that can 

 be said of Eozoon and allied forms is that they may be of organic origin, 

 but it is not yet proved. The same appears to be true of the supposed 

 fossil sponges described by Mr G. F. Matthew from the Laurentian rocks 

 of New Brunswick,* and the reported occurrence of radiolarians and 

 sponges in the pre-Cambrian rocks of Brittany. The discovery of the 

 latter was announced by Dr Charles Barrois,t and later they were de- 

 scribed by Mr L. Cayeux.:j: 



Dr Hermann RaufF made a critical study of the forms described by 

 Mr Cayeux, and came to the conclusion that they were all of inorganic 

 origin. § 



Presence of graphite. — The presence of graphite has frequently been 

 cited as proof of the existence of fucoids in Algonkian time. It is prob- 

 able that in many cases the graphite is of organic origin, but of the char- 

 acter of the life we know nothing. The finest example known to me of 

 the occurrence of graphite in bedded Algonkian rocks is at the mines 4 

 miles west of Hague, on lake George, New York. At the mines the alter- 

 nating layers of graphitic shale or schist form a bed varying from 3 to 

 13 feet in thickness. The outcrop may be traced for a mile or more. 

 The garnetiferous sandstones form a strong ledge above and below the 

 graphite bed. The appearance is that of a fossil coal-bed, the alteration 

 having changed the coal to graphite and the sandstone to indurated, 

 garnetiferous, almost quartzitic sandstones. The character of the graphite 

 bed is well shown in the accompanying plate (22), from a photograph 

 taken by me in 1890. It is here a little over 6 feet in thickness and is 

 formed of alternating layers of highly graphitic sandy shale and schist. 



* Bull. no. 9, Nat. Hist. Soc. New Brunswick, pp. 42-45. 



fSur la presence de fossiles dans le terrain azoique de Bretagne : Comptes rendus des seances 

 de I'Academie des Sciences, 8 aoiit, 1892, 115, pp. 326-328. Gauthier-Villars et Fils, Quai des Grauds- 

 Augustins 55, Paris, 1882. 



t L. Cayeux : Les preuves de I'existence d'organismes dans les terrains preeambrieus : Bull. Soc- 

 Geo). France, 3 ser., 22, 1894, pp. 197-228, with two rocli profiles and plate 11. 



L. Cayeux : Sur la presence de restes de foraminiftres dans les terrains preeambrieus de Bre- 

 tagne. Gomp. rend. Acad. Sci., 118, 1894, pp. 1433-1435, with 6 figures in the text. Ann. Soc. Geol. 

 du Nord, 22, 1894, pp. 116-119, with 6 figures in the text. 



L. Cayeux : De I'existence de nombreux debris de Spongiaires dans le Precambrien de Bretagne. 

 Ann. Soc. Geol. du Nord, 23, 1895, pp. 52-65, with plates 1 and 2. 



g Neues Jahrbuch I'iir Mineralogie, etc., 1896, bd. i, pp. 117-138. 



