J. W. DAWSON ON THE OCCURRENCE OF 



8. Notes on the Occurrence of Eozoon canadense at Cote St. 



Pierre. By J. W. Dawson, LL.D., F.R.S., E.G.S. (Head 



May 12, 1875.) 



[Plate X.] 



Cote St. Pierre, in the Seigniory of Petite Nation, on the river 

 Ottawa, is the locality whence some of the most instructive speci- 

 mens of Eozoon were obtained by the late Mr. Lowe, whose collec- 

 tions are referred to in papers presented to this Society by Sir "W. 

 E. Logan and the writer. Believing that a reexamination of this 

 place would afford a good opportunity for collecting additional speci- 

 mens, and for the study of the fossil in situ, as well as for testing the 

 validity of objections recently raised to the animal nature of Eozoon, 

 I made arrangements for visiting it in September last ; and, through 

 the kindness of Mr. Selwyn, Mr. T. C. "Weston, of the Geological 

 Survey, a skilful collector, and who has had much experience in 

 preparing and examining specimens of Eozoon, was permitted to 

 accompany me, and subsequently prepared slices and photographs of 

 some of the specimens obtained. 



The Lower Lauren tian rocks of this region have been carefully 

 mapped and described in the Reports of the Geological Survey, to 

 which I may refer for their general description. The limestone, 

 which has afforded Eozoon at Cote St. Pierre, is a thick bed belong- 

 ing to the Grenville band of Sir W. E. Logan, and included between 

 the two great belts of orthoclase gneiss (the third and fourth gneiss) 

 which in this region constitute the upper beds of the Lower Lauren- 

 tian. Its average thickness, according to the measurements of Sir 

 "William Logan, is 750 feet ; but it varies from 1500 feet to 60 feet. 

 Its outcrop has been traced in the country north of the Ottawa for 

 at least 100 miles, along several anticlinal and sjmclinal folds*. 



At Cote St. Pierre this limestone occurs on the flank of a hill of 

 gneiss and stratified diorite, with a dip to the south-east at angles 

 of 70° to 80°. The dip, however, is very inconstant, owing to the 

 contortions of the beds. 



The limestone is white and crystalline, and may be described as 

 thin-bedded, since it presents a great number of layers of no great 

 individual thickness, and differing in the coarseness of the crystal- 

 lization and in the presence of dolomite, serpentine, and layers of 

 gneissose matter in some of them. The specimens of Eozoon were 

 found to be abundant in only one bed, not more than four feet in 

 thickness, though occasional specimens and layers of fragments 

 occur in other parts of the band. The exposures are in part natural 

 weathered surfaces seen on a wooded bank, in part an opening 

 made by Mr. Lowe to extract specimens of Eozoon, and a larger 

 opening made, as we were informed, by parties in search of fibrous 

 serpentine, or " rock-cotton," for economic purposes. 



* See map in ' Geology of Canada,' 1863. 



