THE UPPER OK HERMAN BEACHES AND DELTAS. 279 



eastward and northeastward tlu-ough Traverse County and tlie most north- 

 western township of Stevens Covmty, Minn., to Herman, in Grant Connty, 

 nearly 20 miles east of Lake Traverse. From this place the Herman beach 

 runs nearly due north 132 miles to the north side of Maple Lake, in Polk 

 County, about 20 miles east-southeast of Crookston. Beyond Maple Lake 

 the course of this shore-line is known to be nearly east to the south side 

 of Red and Rainy lakes; but it passes through a wooded and 'uninhabited 

 country where it is impracticable to trace its course exactly and determine 

 its height by 'leveling-. 



Along the distance of about 160 miles, as measured by long, straight 

 lines, or about 175 miles, following the larger bends of the shore-line, from 

 Lake Traverse to Herman and Maple Lake, the boundary of Lake Agassiz 

 lies in a prairie region, mostly having a veiy smooth and regular surface, 

 which could not be surpassed in its adaptability for receiving and preserv- 

 ing a record of the old lake level. The Herman beach lines, single on the 

 southern part of the lake border, but double and even quadruple in Clay 

 County and northward, have been carefully mapped across this expanse of 

 prairie, and their heights have been determined by leveling. The principal 

 features of this series of beaches are described in the following pages. 



Especial description i.s also given of the two chief delta deposits of 

 this part of the old lake border. These were brought into the lake, con- 

 temporaneously with the formation of the Herman beach, by the glacial 

 representatives of the Buffalo and Sand Hill rivers. They cover small 

 areas, in comparison with the Sheyenne, Elk Valley, Pembina, and Assini- 

 boine deltas on the west margin of this glacial lake. 



FROM LAKE TRAVERSE EAST TO HERMAN. 



(PLATE XXIII.) 



Within the first 4 miles eastward from the northeast end of Lake 

 Traverse the Herman shore of Lake Agassiz is an eroded bluff of till, 

 rising from the south side of the Mustinka River to a height of 75 to 100 

 feet above the river and lake. The altitude of Lake Traverse at its low- 

 est and highest -stages is 970 and 976 feet above mean tide sea-level. 

 When the lake falls below 973 or 972 feet, which occurs during the diy 



