334 TEE ICE AGE IN NORTH AMERICA. 



With the interpretation which the present discussion has 

 put upon the facts, the following is the order of events : Dur- 

 ing the farthest extension of the ice to the vicinity of the Rocky 

 Mountains, the South Saskatchewan was compelled to flow 

 around the front of the ice-sheet to join the Milk River at 

 the boundary-line near the one hundred and tenth meridian, 

 and thence into the Missouri. A great dry coulee, a portion 

 of which is occupied by a large saline lake known as Peeko- 

 pee, is a marked feature connecting these streams at the 

 present day.* 



Coming eastward to the one hundred and second meridian, 

 the Riviere des Lacs seems, without doubt, to have been the 

 line of drainage for the Souris River for a distance of sev- 

 enty-five or eighty miles. Characteristically enough, this 

 ends northward, near the Souris River, "in a broad dry 

 coulee, which shallows and dies away in a strip of bowlder- 

 covered ground, which stretches northward toward the Souris 

 River, five miles distant, and is somewhat lower than the 

 general surface of the plain." 



At this time there was a lake-like expansion of water in 

 the Elbow of the Souris, covering Renville, Ward, and Mc- 

 Henry counties, Dakota, the evidence of which is still plainly 

 seen. This lake, again, was forced to seek a southern outlet, 

 which it found through a coulee in McHenry county into 

 the head of the Sheyenne River, and thence followed its 

 winding course to Lake Agassiz, near Fargo, where there is 

 an immense delta of river gravel. 



Coming still farther east, the Pembina River occupies a 

 valley very much larger than its present demands ; and, at 

 its junction with the Red River, there is also an immense 

 gravel delta, indicating it as a line of drainage at one time of 

 a far larger area than now. Upon following the valley of 

 the Pembina up, it is found to continue through the Pelican 

 Lake to the Elbow of the Souris, near the one hundredth 



* " Report on the Geology and Resources of the Region in the Vicinity of 

 the Forty-ninth Parallel," pp. 262-268. 



