434 THE GLACIAL LAKE AGASSIZ. 



WESTERN m'cAULEYVILLE SHORES IN NORTH DAKOTA. 



(PLATES XXVII-XXX.) 



My most southern observations of the McCauleyville shore-lines in 

 North Dakota are on tlie hititude of Wahpeton and northward, along the 

 eastern border of the Sheyenne delta. Two levels of Lake Agassiz are 

 indicated by the beaches and escarpments of these shores, the upper being 

 now about 970 feet and the lower about 960 feet above the sea. A beach 

 ridge formed by the lake at the upper level is crossed by the Northern 

 Pacific, Fergus Falls and Black Hills Railroad, about a tliird of a mile 

 west of Mooreton. Its width is about 30 rods, and the elevation of its crest 

 is 974 feet, with descents of 8 feet to the east and 3 feet to the west. This 

 shore continues north and northwest more than 30 utiles along the base of 

 the frontal steep slope of the Sheyenne delta, the erosion of which was 

 completed Ijy the lake waves during this stage. With the Campbell shores, 

 which also run along this border of the delta plateau, it passes 1 to 2 miles 

 west and southwest of Barrett, Colfax, Walcott, and Kindred, and about li 

 miles uorth of Leonard. 



Sand and fine silt of the Sheyenne delta, however, extend to a distance 

 of several miles east of tins plateau, partly as spread originally in the deep 

 central portion of the lake during the Herman stages, when the delta was 

 formed, and partly as redeposited from the erosion of the delta front during 

 the later and lower stages. On tliis nearly flat tract of silt, at a distance 

 of 1^- to 2 miles from the plateau front, the lower McCauleyville shore is 

 marked by a beach ridge, which through most of its observed extent of 

 about 15 miles has become a narrow belt of dunes, occupying a width 

 of 20 to 50 rods and rising 5 to 15 feet above the general level. This 

 belt, running from south to north, is crossed l)y the railway 2.^ miles south 

 of Colfax. Thence it gradually curves northwestward, passing about a 

 half mile east of Colfax and Walcott, and is again crossed by the railway 

 3 miles northwest of Walcott. The land on each side of tlie beach and its 

 dunes has an elevation of 955 to 960 feet, which represents approximately 

 the former water surface. 



As on the opposite portion of the east side of the lake, this latest shore- 

 line, formed during the time of southward outflow, now lies about 10 feet 



