450 THE GLACIAL LAKE AGASSIZ. 



northeast comer of section 26, Alma, northward through the east edge of 

 sections 23 and 14 to the Middle River. This deposit, however, is about 

 15 feet lower than would seem accordant with the Hillsboro beach 5 to 15 

 miles north of Crookston and on the opposite side of the lake in North 

 Dakota, while yet it is distinct from the next lower Emerado beach, which 

 Avas observed at its normal elevation a mile distant to the west. The low 

 position of the Hillsboro beach here may be due to its subdivision in 

 advancing from south t() north, this beach being referable to a secondary 

 Hillsboro stage; otherwise it would imply a noteworthy and very excep- 

 tional irregularity in the crustal uplift. 



Probably the same Hillsboro shore continues north tln-ough the dis- 

 tance of 6 miles to another beach ridge noted on the Tamarack River, in or 

 near the west edge of sections 13 and 12, Wanger. A search witli leveling 

 to the south and north from these localities Avould quite surely prove this 

 shore to be traceable tlu'ougli long distances on the east side of the lake. 



The elevation of the Hillsboro shore where it crosses the Red River, 

 near Holy Cross and Hickson stations, about 15 miles south of I\Ioorhead 

 and Fargo, is approximately 915 feet. Thence its course in North Dakota 

 is iirst northwestwai-d about 20 miles, passing by Horace, to Durbin, on 

 the Maple River. It here lies on an area of line silt, and is not distinctly 

 marked either by a beach ridge or by erosion. 



Along the northwest and north side of the Maple River, at an average 

 distance from it decreasing from 2 miles to 1 mile, a prolonged beach of 

 sand and tine silt (mapped on PI. XXVIII) Avas formed by erosion from the 

 margin of the Sheyenne delta and from the adjoining lake bed, and by 

 transportation toward the northeast and east, being thus built out into the 

 lake as a spit, during the Blanchard and Hillsboro stages. This spit, which 

 is sometimes called the Maple Ridge from its parallelism Avith the Maple 

 River, is crossed by the Great Northern Railway 2 miles nortliAvest of Dur- 

 bin. It is there a Avave-like, massive swell about 50 rods Avide, rising 10 

 feet above the flat expanse on each side, with its top 930 feet aliove the 

 sea, showing that this portion Avas formed during the time of the Blanchard 

 beach. Six miles to the northeast, where it is crossed by the Northern 

 Pacific Railroad at Greene, it has a Avidth of 60 rods, Avith its crest at 919 



