324 On the Geology of the Northwestern Regions of America. 
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, 
together with saliferous marls and beds of gypsum. 
Skirting the base of the Rocky Mountains a remarkable lig- 
nite 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 com- 
pact and splintery, and of a yellowish-white color, 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 Tere- 
bratule, Orihocerata, Encrinites, Caryophyllide, and Lingule, 
as the organic remains brought to England by Franklin’s First 
Expedition; Mr. Stokes and Mr. Sowerby examined those fossils 
which were procured on the Second Expedition, and foun 
amongst them Terebratulites, Spirifers, Corallines, and Maclu- 
rites. The Maclurites were probably the Maclurea magna 0 
Le Sueur and Hall. Sir John Richardson has recently brought 
home from the same quarter a fine specimen of the Receptaculites 
Neptunitt,—a fossil, which, though it occurs abundantly in some 
the Devonian beds of the Hifel, is, with the Maclurite, charac- 
teristic 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 
rom the surrounding prairies, and has been extensively quarried 
for building purposes, it has been distinctly identified as belonging 
to that formation by Dr. Dale Owen, Director of the Geological 
Survey of Wisconsin and Minnesota, who in the course of his 
explorations visited the small colony settled there by the Hudson’s 
Bay Company. In his recently published Report, Dr. Dale enu- 
merates the following fosssils procured by him from the quarries 
at Red River and from Lake Winipeg :— 
1. Fayosites basaltica. 6. Leptena sericea ?} 
: thentnie suleata. 7. —— alternata. 
 ¢ es lycoperdon. 8. —— planoconvexa ! 
4. Pleurorhynchus, sp. 9. Calymene senaria. 
5. Ormoceras Brongniarti. 10. Pleurotomaria lenticularis !? 
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