MOOK, STUDY OF THE M0RBI80N FORMATION 81 



Feet Inches 

 Sandstones, thin, and sandy sliale, with 2 feet of brown sandstone 

 at top 18 



185+ 8 



The Morrison in this locality lies over the Ellis limestone, correspond- 

 ing to the Sundance beds of Wyoming. There is a break below the P'llis, 

 indicating an erosion period of considerable length. 



In the Great Falls region the Morrison has been 

 described by Fisher (1907, 3; 1909, 11; 1909, 13). 

 He gives the following brief description of the out- 

 crops of the Morrison : "The formation is gener- 

 ally exposed in a narrow band on the inner rim of 

 a low ridge formed by the harder overlying rocks 

 of the Kootenie formation. It outcrops all along 

 the base of the Little Belt Mountains from the 

 east end of the district to Smith River. Good ex- 

 posures occur along the upper courses of Sage, 

 Skull, Running Wolf, Hazlett, Surprise, Geyser^ 

 and Otter creeks, and in the bluffs for some dis- 

 tance back from the mountains along Belt Creek, 

 Sand Coulee, Smith River and its tributary, Ming 

 Coulee." The Morrison rests with apparent con- 

 formity on the Ellis "formation, which in turn rests unconformably on 

 Carboniferous beds. The Kootenie overlies the Morrison conformably. 



Fisher gives the following sections : 



Section of the Morrison Formation on the east side of Belt Creole, Montana, in 

 N. E. 14 Sec. 30, T. 18 N., R.l E. 



Feet 



Gray, thin-bedded sandstone 17 



Pebbly conglomerate occurring in lenses 5 



Maroon and green shale 52 



Green shale capped by 1% feet of gray sandstone 5 



Calcareous sandstone, weathering light brown 5 



Green shale 20 



Massive sandstone, weathering light brown 7 



Dark-green shale containing thin limestone layers 9 



Fig. 35. — Section of the 

 Morrison formation in 

 the Electric Goal Field, 

 Montana. 



Scale, 125 feet to 1 Inch. 

 (Calvert.) 



120 



Ellis formation. 



