UPPER SILURIAN AND DEVONIAN AREAS. 73 



of the Niagara formation, oil the lower part of the Saskatcliewan River 

 and on the east side of Lakes Manitoba and Winnipegosis. In the gorge 

 of the Grand Kajjids of the Saskatchewan tins formation, according to 

 Tyrrell, "consists in its lower portion of aboiit GO feet of bnff, yellow, and 

 white limestone, brecciated at the bottom and ripple-marked toward the 

 top. Some bands are highly fossiliferous. * * * The upper portion 

 of the formation consists of a considerable thickness of a compact or jjorous 

 dolomite, often containing many impressions of salt crystals. * * * 

 The highest beds at Stonewall may belong to this terrane."^ 



Overlying the typical Niagara dolomites, Mr. Tyrrell tinds, near the 

 northeastern angle of Lake Manitoba, "a few feet of thick-bedded stroma- 

 toporoid magnesiau limestone holding Pycnostylus Gneljjhensis," which he 

 thinks to be proljably referable to the Guelph formation, next above the 

 Niagara in the Upper Silurian series. 



The succeeding strata of this district, in ascending order, shown to be 

 soft shales in the sections of wells at Rosenfeld and Morden, have not been 

 found in outcrops. These beds doubtless represent higher formations of 

 Ujiper Silurian age and the base of the Devonian system, which latter 

 seems to be identified by fos.sils of the Morden section. 



Devonian strata are reported by Tyrrell on the western shores and 

 islands of Lake Manitoba and Lake Winnipegosis, being especially well 

 exhibited in the islands of Dawson Bay and of Swan Lake, which lies a 

 few miles south of this bay. Above an exposure of a few feet of red 

 shales, the Devonian series in these outcrops comprises 200 feet or more of 

 fossiliferous magnesiau limestone, an overlying thickness of 50 to 70 feet 

 of calcareous shales, whose horizon is marked by many brine springs, and 

 hig-her beds of richly fossiliferous limestone.^ 



All the Paleozoic formations in the lake region of Manitoba, from the 

 St. Peter sandstone to the highest Devonian beds exposed, are stated by 

 Mr. Tyrrell to be "practically conformable and almost undisturbed tlu-ough- 



'" Three Deep Wells iu Manitoba." Trans. Roy. Soe. Canada, Vol. IX, .sec. 4, 1891, p. 91. 



"J. B. Tyrrell, paper before cited; also, Geol. and Nat. Hist. Survey of Canada, Annual Report, 

 new series, Vol. IV, for 1888-89, pp. 21, 22A. J. F. Whiteaves, "Descriptions of some new or previ- 

 ously unrecorded species of fossils from the Devonian rocks of Manitoba," Trans. Roy. Soc. Canada, 

 Vol. VIII, sec. 4, pp. 93-110, with seven plates. 



