AMERICAN GEOLOGY DECADE OF 1860-1869. 521 



Naturally, Murray's observations were limited mainly to a compar- 

 atively narrow belt along- the coast. W ith the exception of the Glacial 

 and post-Glacial material, no formations were found of later date than 

 the Carboniferous. The succession of the Lower Silurian formations 

 of the island from above downward he gave as follows: Sillery, Lau- 

 zon, Levis, Upper Calciferous, Lower Calciferous, Upper Potsdam, 

 Lower Potsdam, and St. John's Group. The St. John's Group is now 

 recognized as Middle Cambrian (?), while his Lower Potsdam is Lower 

 Cambrian. 



Before the beginning of Murray's work it had already been shown 

 by Richardson, working under direction of Logan, that a trough of 

 Lower Silurian rocks must underlie the northern part of the Gulf of 

 St. Lawrence, gradually narrowing toward the Strait of Belle Isle, one 

 side of the trough rising on the coast of Labrador, while the other 

 formed the western shore of Newfoundland from Bonne Bay to Cape 

 Norman. On each side of the Strait these rocks were found to rest 

 on Laurentian gneiss, which was ascertained to extend from the neigh- 

 borhood of Bonne Bay to within 12 or 15 miles of Hare Bay. 



Murray's investigations proved that the Laurentian rocks spread in 

 breadth to the Atlantic coast of the great northern peninsula of the 

 island, and that the base of the Lower Silurian strata, sweeping around 

 the northern extremity of the gneiss, comes upon the coast near Canada 

 Bay, and again strikes into the land at Coney Arm in White Bay, 

 w T here the Lower Silurian are overlaid by Upper Silurian, followed 

 by rocks of Devonian age. Farther to the southeast the Laurentian 

 and Silurian series were found to be partially and unconformably cov- 

 ered by rocks of Carboniferous age. 



The report was accompanied by a colored geological map on ten 

 sheets, on a scale of 25 miles to the inch. 



As already noted, the Canadian geologists, with the exception of 

 Logan, have never taken kindly to the idea of a glacial ice sheet, but 

 have sought to account for the distribution of the drift, erosion, and 

 allied or associated phenomena through other means. 

 Gfa^fa «on V !864. on Tnus > J - W - Dawson, in his address before the Nat- 

 ural History Society of Montreal in 1864, took occasion 

 to combat vigorously the idea, on the ground that " it requires a series 

 of suppositions unlikely in themselves and not warranted by facts;" 

 that it seems physically impossible for a sheet of ice to move over an 

 Dawson's Address even surface, striating it in uniform directions over 

 rnstory societyof vas ^ areas i that glaciers could never have transported 

 Montreal, 1864. £ ne } ar g- e bowlders and left them in the positions found, 

 having no source of supply; that the peat deposits, fossils, etc., show 

 that the sea at that period had much the same temperature as the pres- 

 ent Arctic currents, and that the land was not covered by ice. - 



