J. B. Tyrrell — Cretaceous of Manitoba. 231 



many beds of septarian ironstone nodules, but very few of 

 these nodules are compact like those in the Millwood Series, 

 but are generally cut by numerous veins of crystalline calcite. 

 !N"o fossils were found by the writer in these shales. 



The cliffs of this terrane generally weather with a more or 

 less sloping surface, but in railway cuttings or by some streams 

 where erosion is very rapid, they rise almost vertically, present- 

 ing a general lead-gray appearance. The beds are also much 

 fissured, and iron-stains are everywhere seen along the lines of 

 fissure. On a fresh surface the shale can be readily cut, but it 

 quickly hardens on exposure to the atmosphere, and the streams 

 cutting through it have their banks strewn with lenticular peb- 

 bles derived from it. In some places, as in the valley of the 

 Little Saskatchewan River, alluvial beds of these pebbles are 

 being used as ballast for the railway. 



The Odanah Series is of considerable economic importance 

 to the country, as, being very much fissured, it allows water to 

 flow readily through it, and is thus the source from which 

 many of the wells in western Manitoba obtain their supply of 

 water. It is well shown west of the escarpment on both the 

 Pembina and Riding Mountains, but probably on account of 

 the paucity of sections, it has not yet been recognized farther 

 north. 



The whole thickness of the Pierre in Manitoba is about 1000 

 feet. The Millwood Series, as seen on the northern face of 

 the Riding Mountain, has a thickness of between 450 and 500 

 feet, while about 300 feet of the overlying Odanah series is 

 there also seen, reaching near to the summit of the mountain and 

 being immediately overlain by the drift deposits. The top of 

 the Odanah series is not seen in the Riding Mountain, but 

 farther south Dr. Dawson gives the thickness of the upper 

 portion of his Pembina Mountain group, which represents this 

 series, as at least 300 feet.* 



At the village of Deloraine in southwestern Manitoba and 

 close to the northern face of the Turtle Mountain, the Tank- 

 well on the Pembina Mountain branch of the Canadian 

 Pacific Railway strikes the Odanah shales at a depth of about 

 90 feet, and a deep well close beside it does not strike the 

 Niobrara till a depth of 1000 is reached, giving a thickness for 

 the Pierre of 910 feet. At the foot of the Turtle Mountain a 

 band of hard gray calcareous sandstone crops out in various 

 places, and taking this to represent the base of the Laramie, 

 though no fossils have as yet been recognized from it, the 

 whole thickness of the Pierre would be given at a little more 

 than 1000 feet. Considering the Millwood Series as having a 



* Report on the Geology and Resources of the 49th Parallel, by G. M. Dawson. 

 p. 85. MoDtreal: 1875. 



