1898.J PECKHAM — THE GENESIS OF BITUMENS. 115 



abundantly disseminated, is an evidence of the elimination of 



sulphates by evaporation The brines of the valley of the 



Allegheny river, obtained from borings in the coal formation, are 

 remarkable for containing large proportions of chlorides of calcium 

 and magnesium, though the sum of these, according to the examples 

 given by Lenny, is never equal to more than about one-fourth of 

 the chloride of sodium. The presence of the sulphates of barium 

 and strontium in these brines, and the consequent absence of solu- 

 ble sulphates, is, according to Lenny, a constant characteristic in 

 this region over an area of 2000 square miles. "^ 



Among many other illustrations that might be given of these 

 non-sulphated palaeozoic waters, I mention one which was obtained 

 from a boring on Great Manitoulin island in Lake Huron, at a 

 depth of 192 feet, ''After passing through the black slates of the 

 Utica formation, and for sixty feet into the underlying Trenton 



limestone It contained no sulphates nor barium nor stron- 



tium." Another palaeozoic water of a very different character was 

 obtained from a well bored for petroleum at Bothwell, Ontario, in 

 1865. ^' At a depth of 475 feet from the surface, and probably at 

 or near the base of the Corniferous limestone, a copious spring was 

 met with of very sulphurous water and a little petroleum." The 

 water contained sulphate of calcium and sulphides of sodium and 

 hydrogen. Waters apparently similar are pumped from several of 

 the oil wells in the vicinity. ''The sulphurous impregnation is 

 doubtless to be ascribed to the reducing action of hydrocarbonace- 

 ous matter upon the sulphates which the waters contain."^ 



9. A brief examination of the superposition of the palaeozoic 

 and earlier formations of North America will show the Laurentian, 

 embracing the oldest known rocks of the globe, outcropping from 

 the coasts of Labrador to Lake Superior and over a large ai-ea in 

 northern New York. Associated with this system is the Norian, 

 which is characterized by a great development of opalescent feld- 

 spars. Above these are the Green Mountain series, an inferior part 

 of the Lower Silurian, which corresponds wholly or in part to the 

 Huronian system of Canada and the region about Lake Superior. 

 Above them are the White Mountain series, which are Upper Silurian 

 and perhaps Devonian. These formations constitute for the most 



1 Bischof, Chem. and Phys. Geol., i, 337. Hunt, Chein. and Geol. Essays, 

 p. 121, ed. 1875. '^"^' Jour. Set., March, July and Sept., 1865. 

 "^Essays, 158-163, ed. 1875. 



