1855.] ISBISTER — NORTH AMERICA, ETC. 507 



Lake Superior. After passing the straits of Lake Winipeg, we have 

 granitic rocks on the east shore and Silurian rocks on the west and 

 north, the basin of the lake being mostly excaA^ated in the limestone. 

 The granite and gneiss which form the east shore of Lake Winipeg 

 strike off at its N.E. corner, and, passing to the north of Moose 

 Lake, go on to Beaver Lake, where the boat-route again touches 

 upon them. The extension of the limestone in a westerly direction 

 from Lake Winipeg has not been ascertained ; but it has been traced 

 as far up the Saskatchewan as Carlton House, where it is at least 

 280 miles in breadth. Beyond this it is either succeeded or covered 

 by cliffs of calcareous clay, which bear some resemblance to those 

 found along the banks of the upper portions of the Missouri, toge- 

 ther with saliferous marls and beds of gypsum. 



Skirting the base of the Rocky Mountains a remarkable lignite 

 formation is met with, which is said to extend through the valley of 

 the Mississippi and of Mackenzie River as far north as the Arctic Sea. 



The limestone of Lake Winipeg, which undoubtedly covers a vast 

 tract of country, may in general be characterized as compact and 

 splintery, and of a yellowish- white colour, passing into buff, and 

 sometimes of an ash-grey, mottled, or banded with patches of light 

 brown. In the district between Lake Winipeg and the Saskatchewan, 

 more particularly examined by the Arctic Expeditions of Franklin 

 and Back which passed through it on their way to the Arctic Sea, 

 the limestone strata were found to be almost everywhere extensively 

 exposed, and to be remarkably free from intrusive rocks. Professor 

 Jameson enumerates TerebrafulcB, OrtJiocerata, Encrinites, Caryo- 

 phyUitce, and Lingulce, as the organic remains brought to England 

 by Franklin's First Expedition ; Mr. Stokes and Mr. Sowerby ex- 

 amined those fossils which were procured on the Second Expedition, 

 and found amongst them Terebratulites, Spirifers, Corallines, and 

 Maclurites. The Maclurites were probably the Machirea ynagna 

 of Le Sueur and Hall. Sir John Richardson has recently brought 

 home from the same quarter a fiae specimen of the Beceptacutites 

 neptunii, — a fossil, which, though it occurs abundantly in some of the 

 Devonian beds of the Eifel, is with the Maclurite characteristic in 

 Canada, as in New York, of the Lower Silurian. 



Along the southern shores of Lake Winipeg and in the Valley of 

 the Red River, where the limestone rises in solid ledges from the 

 surrounding prairies, and has been extensively quarried for building 

 purposes, it has been distinctly identified as belonging to that forma- 

 tion by Dr. Dale Owen, Director of the Geological Survey of Wiscon- 

 sin and Minnesota, who in the course of his explorations visited the 

 sm.all colony settled there by the Hudson's Bay Company. In his 

 recently published Report, Dr. Dale enumerates the following fossils 

 procured by him from the quarries at Red River and from Lake 

 Winipeg : — 



1. Favosites basal tica. 5. Ormoceras Brongniarti. 



2. Coscinopora sulcata. 6. Leptaena sericea ? f 



3. Chffitetes lycoperdon. 7. alternata. 



4. Pleurorhynchus, sp. 8. planoconvexa ? 



VOL. XI, PART I. 2 M 



