THI] TINTxVH BEACHES IN MINNESOTA. 397 



delta saiiil niid gravel, brought by the glacial representative of the Shey- 

 enue River, apparently at the time of formation of the Dovre nK)raiue, when 

 the retiring ice-sheet began to uncover the edge of the area of Lake Agassiz 

 (p. 150). Previous to the lower Tintah stage of the lake, the River Warren, 

 outflowing by two broad channels, one south and the other west of this 

 plateau, had eroded the upper portion of the valleys, respectively 2 and 4 

 miles wide, which are occupied by the Mustinka and the Bois des Sioux. 

 At the time of the lower Tintah beach and during the later Campbell and 

 SIcCauleyville stages the River Warren outflowed wholly west of this 

 tract, completing the erosion of the valley of the Bois des Sioux from 

 Wliite Rock south to Lake Traverse, where it now contains a great marsh 

 with numerous permanent areas of water 1 to 3 miles in length. 



In the south half of section 2, township 128, range 47, at a distance of 

 about 1^ miles east of Wliite Rock, the upper Tintah shore bears a welL 

 defined beach ridge of sand and gravel, lying on a surface of till. This 

 ridge is 15 to 20 rods wide, rising 3 feet above the surface on each side, 

 with its crest about 1,015 feet above the sea. Thence it was traced nearly 

 4 miles in a curving course to the northeast and east, passing through 

 sections 31 and 32, Taylor. At the center of section 31, Mr. David War- 

 riner's farm buildings are situated on its top, which has a height of 5 to 8 

 feet above the surface of till at the south and north. His well shows that 

 the beach gravel and sand reach to a depth of 10 feet. In this vicinity the 

 beach is somewhat irregular in its development and varies from 10 to 30 

 rods in width. Other irregular sand and gravel deposits belonging to this 

 shore-line were found extending from south to north in sections 21 and 16, 

 Taylor, lying on a tract of till slightly elevated above long sloughs on the 

 south and east. 



Two very small beach ridges, from 1 to 3 feet high, consisting of sand 

 and gravel on a nearly flat surface of till, are crossed hj the Evansville 

 and Tintah line of the Great Northern Railway, about 1\ miles and 1 mile 

 east of Tintah.^ The heights of their crests are respectively 1,010 and 

 1,007 feet above the sea. On the Minneapolis and Pacific Railway, 2 miles 



' A Dakota name meaning prairie (A. W. Williamson in Thirteenth Annual Keport, Geol. and 

 Nat. Hist. Survey of Minnesota, for 1884, p. 110). 



