PREGLACTAL VALLEY OF LITTLE MISSOURI RIVER 301 



tionecl by Wilder, 6 who saw one end of it in 1903, but its course was not 

 explored. 



During the summer of 1914 this old valley was mapped in detail by 

 the writer and a line of levels was run from the south edge of the Eay 

 quadrangle to the Little Missouri Elver. The valley extends from the 

 mouth of Bowling Creek north and east to the Missouri Eiver at the 

 mouth of Tobacco Garden Creek, a distance measured along the axis of 

 the valley of 55 miles. Its bottom varies in width from half a mile to 

 one and three-quarters miles and throughout much of its course it is a 

 mile or more wide. 



Two very low and inconspicuous divides are present in this valley, one 

 between Tobacco Garden and Cherry creeks and another between Cherry 

 and Eedwing creeks. The former is between 3 and 4 miles north of 

 Schafer, where the divide is less than 20 feet above Cherry Creek. Even 

 more flat is the divide separating the headwaters of Cherry from those of 

 Eedwing Creek, which is located about two miles south of Elsworth. For 

 a distance of 3 to 4 miles along the valley floor the elevation does not 

 vary more than 4 or 5 feet, and so flat is this interstream area in the old 

 valley that the water does not run off after a rain, but stands on the 

 surface until it sinks into the ground or evaporates. 



The present divide between Eedwing and Bowling creeks constitutes 

 the highest point in the old river valley. Its elevation is 2,191 feet above 

 sealevel, or 177 feet above the Little Missouri at the mouth of Bowling 

 Creek. In that portion now occupied by Cherry Creek the average slope 

 of the valley floor is 7.4 feet per mile for a distance of 20 miles, while in 

 that portion occupied by Tobacco Garden Creek the slope averages 5.5 

 feet per mile. 



Abnormal Drainage Features of Little Missouri Tributaries 



The upper valleys of both Squaw and Eedwing creeks open out into 

 this preglacial valley of the Little Missouri, so that the floors of these 

 valleys tributary to the Little Missouri are continuous with the broad 

 flats of Cherry Creek. The explanation of this peculiarity, in the case of 

 Eedwing Creek, is found in the fact that this youthful and vigorous 

 stream, with a fall of 23 feet per mile, has worked its way back by head- 

 ward erosion and taken possession of a portion of the flats forming the 



The lignite of North Dakota and its relation to irrigation. Water Supply and Irri- 

 gation Paper No. 117, U. S. Geol. Surv., p. 43 ; also Third Biennial Report, North Dakota 

 Geol. Surv., map, p. 16. 



