14 A. G. LEONARD 



the Lance is non-marine and lignite-bearing and has been named the 

 Ludlow lignitic member/ The Cannonball marine and Ludlow 

 lignitic members occupy similar stratigraphic positions and are 

 believed to be contemporaneous in age. 



The lower part of the Lance is T^est exposed in the badlands 

 bordering the Little Missouri River in Bowman and Slope counties, 

 where it is composed of shales alternating with soft gray or yellow 

 sandstones, the beds having a notably dark and somber aspect. 

 The prevailing colors are dark gray, but beds of brown carbonaceous 

 shale are common and conspicuous. Much dark brown ferruginous 

 material is present, occurring both in thin seams and concretions, 

 the latter being most numerous at certain horizons, and fragments 

 of this cover the slopes in many places. Another characteristic 

 is the great number of sandstone concretions, some small and others 

 8 to lo feet in diameter. Only occasional thin seams of lignite 

 are found in the lower part of the Lance. 



The Ludlow lignitic member in North Dakota is similar litho- 

 logically to the lower part of the Lance except that numerous beds 

 of lignite are present. In western Slope County it contains at 

 least 5 lignite beds which are from 4 to 30 feet in thickness. 



The flora of both the lower part of the Lance and the Ludlow 

 lignitic member is similar to that of the overlying Fort Union, the 

 great majority of the species being common to both formations, 

 according to Knowlton.^ The Lance thus has a Fort Union flora. 

 The characteristic vertebrate fossils of the Lance are the three- 

 horned dinosaur Triceratops. Trachodon bones are also present in 

 these beds. 



The Cannonball marine member has been mapped only west of 

 the Missouri River, and while, in the absence of outcrops, it is not 

 represented on the geologic map as occurring east of the river, 

 it seems not unlikely that it may be present beneath the drift, and 

 that a portion of the area mapped as the lower member of the Lance 

 is occupied by the Cannonball marine member. On account of 



' E. R. Lloyd and C. J. Hares, "The Cannonball Marine Member of the Lance 

 Formation of North and South Dakota and Its Bearing on the Lance-Laramie Prob- 

 lem, Jour. GeoL, XXIII (1915), 523-47. 



' Proc. Wash. Acad. ScL, XI (1909), 218-24. 



