490 J. E. TODD THE CHANNEL OF THE MISSOURI RIVER 



structed or dammed by the ice and changed into lakes, Avhich would fill 

 rapidly, not only from the glacier, but from the rainfall of regions farther 

 west; so that in a short time each prominent river basin would contain 

 a good-sized lake. Because of the eastward slope of the country, these 

 different lakes w^ould become deeper first next the ice, and the connecting 

 streams escaping from the lakes would be first in the close vicinity of the 

 ice. We may suppose that the line of lakes in both of the Dakotas would 

 have several phases of development with each particular stage, but more 

 or less contemporaneous through them all; and yet it would take longer 

 for a large lake to pass through certain stages than a smaller and simpler 

 one. 



THE NIOBRARA RIVER AXD RED LAKE 



In the early stoppage of the stream we may suppose that the Niobrara 

 River and Eed Lake may have developed more promptly, although they 

 may have begun later than the lakes farther north. They were able to 

 cut through their respective barriers more promptly, and thus prepare the 

 way for the draining of the lakes farther north. 



It is probably unnecessary to attempt to give the lakes in detail or in 

 order, referring instead to the maps and remembering that the phase 

 during the old history must have changed frequently. It may not be 

 necessary to do more than call attention to some more striking points. 



We find evidence that the Yellowstone and the Missouri west of the 

 Little Missouri became dammed by the ice on the north, which caused 

 an overflow into the valley of the Little Missouri. Leonard has assumed 

 that the valley of the Little Missouri was Pleistocene, whereas we take 

 it that its Tertiary channel was by way of Tobacco Garden Creek and 

 northward until it found the Yellowstone. When the ice advanced, it 

 dammed the course of the Little Missouri and formed a lake, which 

 received water for a time from the Missouri Eiver and the Yellowstone 

 through the Benny Pierre-Hay Draw outlet. 



The outlet of Little Missouri Lake was along the present course of the 

 Little Missouri eastward. Patches of numerous boulders are found here 

 and there marking the course of the Little Missouri around northeast and 

 south of the Kildeer Mountains. Probably at its early stage it emptied 

 into Knife River Lake, this lake in turn passing over into Heart River, 

 and so on southward into Lake Arikaree. An old shoreline of this lake 

 seems to have been the origin of Farmers Valley and of the escarpment 

 south of it. As the lakes had their outlets cut down more and more, 

 one marked effect would be that these outlets would be on the side next 

 the glacier, for not only would the slope of the country tend to throw 

 them farther east, but also the streams on that side would be much more 



