J. W. DAWSON ON THE PHOSPHATES OF CANADA. 285 



33. Note on the Phosphates of the Laurentian and Cambkian 

 Rocks of Canada. By J. W. Dawson, LL.D., E.R.S., F.G.S. 

 (Read March 22, 1876.) 



The extent and distribution of the deposits of apatite contained in 

 the Laurentian of Canada and in the succeeding Palaeozoic forma- 

 tions, have not escaped the notice of our Geological Survey, and 

 have been referred to in some detail in Reports of Mr. Yennor. 

 Mr. Richardson, and others, as well as in the General Report 

 prepared by Sir W. E. Logan in 1863. Some attention has also 

 been given, more especially by Dr. Sterry Hunt, to the question of 

 the probable origin of these deposits*. My own attention has been 

 directed to the subject by its close connexion with the discussions 

 concerning Eozoon ; and I have therefore embraced such opportunities 

 as offered to visit the localities in which phosphates occur, and to 

 examine their relations and structure. I would now present some 

 facts and conclusions respecting these minerals, more especially in 

 their relation to the life of the Laurentian period, but which may 

 also be of interest to British geologists in connexion with the facts 

 recently published in the ' Journal ' of this Society in relation to 

 the similar deposits found in the Cambrian and Silurian of Wales f . 



In the Low T er Silurian and Cambrian rocks of Canada phosphatic 

 deposits occur in many localities, though apparently not of sufficient 

 extent to compete successfully for commercial purposes with the 

 rich Laurentian beds and veins of crystalline apatite. 



In the Chazy formation, at Alumette Island, and also at Gren- 

 ville, Hawkesbury, and Lochiel, dark-coloured phosphatic nodules 

 abound. They hold fragments of Linyulo*, which also occur in the 

 containing beds. They also contain grains of sand, and, when 

 heated, emit an ammoniacal odour. They are regarded by Sir W. 

 Logan and Dr. Hunt as coprolitic, and are said to consist of " a paste 

 of comminuted fragments of Lvngulce, evidently the food of the 

 animals from which the coprolites were derived" J. It has also 

 been suggested that these animals may have been some of the larger 

 species of Trilobites. In the same formation, at some of the above 

 places, phosphatic matter is seen to fill the moulds of shells of 

 Pleurotomaria and Holopea. 



In the Graptolite shales of the Quebec group, at Point Levis, 

 similar nodules occur; and they are found at Riviere Ouelle, 

 Kamouraska, and elsewhere on the Lower St. Lawrence, in lime- 

 stones and limestone conglomerates of the Lower Potsdam group, 

 which is probably only a little above the horizon of the Menevian 

 or Acadian series. In these beds there are also small phosphatic 

 tubes with thick walls, which have been compared to the supposed 

 worm-tubes of the genus Serpidites§. 



* Geology of Canada, 1863; Chemical and Geological Essays, 1875. 

 t Davies & Hicks in Quart. Journ. Geol. Soc. August 1875. 

 } Geology of Canada, p. 125. 



§ Geology of Canada, p. 2£9; Richardson's Report, 1869. 



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