22S J. B. Tyrrell — Cretaceous of Manitoba. 



recognized. The following are the groups with their approxi- 

 mate maximum thicknesses. 



Laramie ? . 



p- „ ro ( Odanah 500 feet. 



rieire ] Millwood.... 500 " 



Niobrara 540? " 



Benton 130 " 



Dakotah 200 " 



The Dakotah Group, resting unconformably on the lime- 

 stones of the Devonian, is composed of white or reddish sand- 

 stones either cemented by a calcareous matrix or often quite 

 incoherent, being then an even-grained white quartzose sand. 

 This grades up into a light green and rather hard sandstone, 

 commonly interstratified with thin bands of shale. 



Very few fossils have been found in this sandstone, and 

 what have been found are confined to the greenish upper beds. 

 They consist chiefly of carbonized fragments of wood and conif- 

 erous leaves ; but the following animal remains have also been 

 collected, viz : Lingula subsjpatulata f H. & M., Ostrea con- 

 gests, Con., Modiola te?iuisculpta, Whit, and cycloid scales of 

 fishes.* 



The terrane can be seen in several exposures along- the foot 

 of the northern portion of the Cretaceous escarpment, and at 

 a small island known as Pemican Island in lake Winnipegosis, 

 forty-four miles east from the foot of the escarpment there are 

 evidences of the presence of this or the overlying group. The 

 exposures seen were altogether too few and small to allow of 

 any exact determination being made of the total thickness of 

 the group, but on account of the irregularities of the floor on 

 which it was laid clown it certainly varies greatly even in short 

 distances. Near the northwest end of Lake Winnipegosis it 

 has probably a maximum thickness of two hundred feet, while 

 on the north side of the Riding Mountain, where it was passed 

 through in the Manitoba Oil Co's well on Yermillion River, 

 it has, so far as can be determined from the few specimens at 

 hand, a thickness of fifty-five feet. 



South of this point, which is almost on the line of the 51st 

 parallel of north latitude, these sandstones have not been 

 recognized in the province, but as they are again reported as 

 occurring in Dakota and farther south, they are in all prob- 

 ability continuous throughout the Cretaceous areas of Manitoba. 



Overlying the sandstones of the Dakota, the Benton Group 

 occurs as a band of dark gray, almost black, shale holding a 



* For the determination of all the fossils in the paper, except the Foraminifera 

 and Radiolaria, I am indebted to Mr. J. F. Whiteaves, the Paleontologist of the 

 Canadian Geological Survey. 



