THE CEETACEOUS AREA. 81 



WELL AT MORDEN, MANITOBA. 



Mordeii is due west of Rosenfeld at a distance of 24 miles, lying on 

 the border of the broad plain which extends from the Red River to the 

 Pembina Mountain. Its elevation is 978 feet a]:)ove the sea. A well,. 

 repoi-ted by Tyrrell, was drilled here to the depth of 600 feet, during the 

 winter and spring of 1889-90, with the hope of obtaining artesian water. 

 Its section was alluvial sand and fine gravel, 15 feet; till, 16 feet; gray 

 Cretaceous shales, referred to the base of the Fort Pierre formation and 

 the next lower Niobrahx and Fort Benton formations, 289 feet; the 

 white Dakota sandstone, 92 feet; and red and gray shales, with porous 

 limestone; representing, as shown by their fossils, probably the base of the 

 Devonian system, 188 feet. The westward dip of the strata in the Hum- 

 boldt and Rosenfeld wells carries them beneath the bottom of the Morden 

 w^ell. No artesian flow was obtained at Morden, but from the top of the 

 Dakota sandstone strongly saline water rose to within 6 feet of the surface. 



CRETACEOUS FORMATIONS. 



Cretaceous beds- lie on the west border of the Archean rocks in Min- 

 nesota; and farther north, along the west side of the lower part of the Red 

 River Valley and of Lakes 'Manitoba and Winnipegosis, they rest upon the 

 Lower and Upper Silurian and Devonian strata that form the floor of this 

 broad, flat valley, beneath its glacial, lacustrine, and fluvial deposits. 

 Thence northwestward to the Mackenzie and the ocean Cretaceous beds 

 border and overlie the west part of the Silurian and Devonian belt. West 

 of Lake Agassiz the Cretaceous area has a width of 600 to 700 miles, 

 including the entire region of the elevated plains, and terminating at the 

 east base of the Rocky Mountains. 



Marine series of the Upper Missouri. — In the region of the Upper i\Iis- 

 souri River, formations belonging to the middle and later portions of the 

 Cretaceous period are well developed. Meek and Hayden there identified 

 five members of this system, in descending order as follows:^ The Fox 

 Hills formation, gray, ferruginous, and yellowish sandstone, and arena- 



' Report of the U. S.-Geological Survey of the Territories, 1870, p. 87. 

 :M0X XXV G 



