Section IV, 1891. [ 91 1 Trans. Eoy. Soc. Canada. 



Y III. — Three Deep Wells in Maniioha. 

 By J. B. T_YRRELL, M.A., B.Sc, F.G.S. 



(Communicated by Dr. G. M. Dawson and read May 28, 1891.) 



Introduction. 



(Gave a short accouut of the pre-tertiary geology of Manitoba, of which the following 

 is an abstract.) 



The eastern side of Lake Winnipeg consists of Laïii'entian gneisses and granites, and 

 Keewatin traps, agglomerates, quartzose sandstones, conglomerates, etc. The undulating 

 surface of these crystalline rocks declines gently to the west beneath the palœozoic beds. 



The palsBOzoic rocks consist of the following series : — 



Chazij (St. Peters) formation, represented by about a hundred feet of white quartzose 

 sandstone, with generally well-rounded grains, running down, at the bottom, into a 

 quartzose conglomerate. 



Trenton formation, consisting at the bottom of a mottled buff and grey dolomitic 

 limestone, found at Big and Swampy Islands, etc., and probably also at Ea.st Selkirk, 

 above which are other horizontal evenly bedded limestones and dolomites, amounting in 

 all to a few hundred feet, and all more or less rich in fossils. 



Hudson River Formation represented by less than a hundred feet of fossiliferous 

 shales and dolomites. 



Niagara formation, recently discovered by the writer on the lower part of the 

 Saskatchewan river, and on the east side of Lakes Winuij^egosis and Manitoba. As shown 

 in the gorge of the Grand Rapids, it consists in its lower portion of about sixty feet of 

 buff, yellow, and white limestone, brecciated at the bottom, and ripple-marked towards 

 the top. Some bands are highly fossiliferous, Pentamerus deciissutus being the most plenti- 

 ful and characteristic species, though its vertical range is very small. Tlie upper portion 

 of the formation consists of a considerable thickness of a compact or porous dolomite, 

 often containing many impressions of salt crystals. Its most typical fossils are Isochilina 

 grandis, Leperditia Hisingeri and Stro/ihomena acanlhoptera. The highest beds at Stonewall 

 may belong to this terrane. 



Guelph. — Near the northeastern angle of Lake Manitoba the typical Niagara dolomites 

 are overlain by a few feet of thick-bedded stromatoporoid maguesian limestone holding 

 Pycnostylm Guelpliensis, which may be of the above age. 



Over these Silurian limestones there is in the lacustral region a gap in the known 

 section, probably due to the presence of soft argillaceous shales. A few feet of soft red 

 shales are the first beds seen above this gap, and are apparently of Devonian age. 



