CRETACEOUS AND TERTIARY FORMATIONS 523 



Feet Inches 



Soil, sandy 3 



Sand, Pleistocene 20 



Shale, gray and black, mottled; arenaceous in part, the sand 

 being very fine ; sandy layers have yellow color. Some por- 

 tions contain considerable carbonaceous material, which 

 gives the rock its black color. Shale cut by several sets of 

 joints running irregularly in many directions, but all making 

 large angle with the horizontal. These joint cracks are filled 

 with gypsum and the sides stained with iron. The mottled 

 character shows on weathered face of the bluff, where there 



are large blotches of black on the gray surface 28 



Shale, dark gray and yellow, some layers sandy; more thinly 



bedded than overlying member 7 6 



Sandstone, soft, fine-grained, gray, and yellow 7 6 



Sandstone, argillaceous, forming hard projecting ledge 2 



Shale, dark gray to black, alternating with bands of laminated, 



fine-grained, yellow sand 3 



Shale, dark gray to black, when moist 9 6 



Sandstone, soft and incoherent, yellow 1 



Unexposed to river level 27 



Total 108 6 



In the vicinity of Long Lake, in southeastern Burleigh County, 

 and in the railroad cuts along the Linton Branch of the Northern 

 Pacific, in northern Emmons County, the sandstone and shales 

 of the Lance formation are well exposed, and they outcrop at a 

 number of points about Linton. The eastern boundary can be 

 determined only approximately on account of the heavy mantle 

 of drift, which covers the bed-rock. 



The Lance formation of south-central North Dakota, as shown 

 on the foregoing pages, consists of three members: an upper sand- 

 stone about one hundred feet thick, a middle member composed 

 of dark shales with a few sandstone layers and having a thickness 

 of 200 to 250 feet, and a lower member made up of shales and sand- 

 stone in alternating layers. This latter member has a thickness 

 of 350 feet or over, and the maximum thickness of the entire Lance 

 formation is probably not far from 700 feet in this region. 



Fossils occur sparingly in this area. A portion of the tibia of 



