LATE TERTIARY HISTORY OF UPPER MISSOURI RIVER 55 



lowed the present course of the Missouri River to WilHston, thence 

 northward along the valley of Muddy Creek, which is much too 

 wide for the stream that now occupies it. The writer has not traced 

 this portion and was unable to get definite information on the old 

 valley of the Yellowstone more than a few miles north of Wil- 

 liston.^ However, Lambert, in Exploration for the U.S. Pacific 

 Railroad in 1853, mentions a wide valley, discovered by Lander, 

 which crosses the Coteau connecting the Souris with the Missouri 

 near old Fort Union (Williston?) It seems probable, therefore, 

 that the ancient stream proceeded north or northeastward from 

 this point. 



Concerning the course of the Tertiary ancestor of the Little 

 Missouri River, the evidence is very plain. An old valley, several 

 miles in width, extends northward from the first prominent eastward 

 bend of the present stream near the mouth of Bowlin Creek to the 

 head of Tobacco Garden Creek and thence along this valley to the 

 present Missouri and probably joins the Tertiary Yellowstone near 

 WilHston. This old valley south of the Missouri River was first 

 noted by F. A. Wilder,^ who describes it as being evidently a former 

 course of a prominent stream similar to the Little Missouri. 



The present valley of the Little Missouri River from the Kildeer 

 Mountains east to its mouth is narrow and bordered by rugged 

 badlands of soft Fort Union strata. Consolidated glacial drift 

 occurs on the jagged tops of some of the ridges 250 feet high and 

 within one-half mile of the stream channel, but nowhere on the 

 sides of the valley has consolidated drift been found. Although 

 there are no terraces in this portion of the valley, in the vicinity 

 of Medora and continuing southward into South Dakota a well- 

 defined terrace from a few feet to several miles in width has been 

 mapped by C. J. Hares.^ Along Little Beaver Creek, one of the 

 tributaries of the Little Missouri, the remaining fragments of this 



' F. H. H. Calhoun, "The Montana Lobe of the Keewatin Ice Sheet," U.S. Geol. 

 Survey., Prof. Paper jo, pp. 35, 36, 1906. 



^ F. A. Wilder, "The Lignite of North Dakota and Its Relation to Irrigation," 

 U.S. Geol. Survey, Water Supply, Paper iiy, p. 43, 1905. 



3 C. J. Hares, "Lignite in Southwest North Dakota," U.S. Geol. Survey Bull. 

 (in preparation) . 



