YELLOW MEDICINE, LYON AND LINCOLN COUNTIES. 



BOH 



Channels through the outer moraine. ] 



Channels through tlie outer moraine. This morainic belt, and the thick sheet, of till which is 

 massed against its west side and descends thence westward, are cut in the west part of Lake Ben- 

 ton township by a deep channel or valley, which is called, translating its Sionx name, the "Hole in 

 the Mountain." The railroad between Lake Benton and Verdi goes south-southwest four miles 

 through this gap, bounded on each side by picturesque bluffs which are buttressed by steep spurs 

 and cut by deep tributary ravines. Its depth, wholly in the glacial drift, is from 150 to 200 feet 

 below the knolly surface of the moraine, and its highest point is about ten feet above lake Ben- 

 ton, which has its outlet eastward into the Redwood river. This valley, from an eighth to a 

 fourth of a mile wide, was evidently excavated by a river that flowed from northeast to southwest 

 across this great ridge, which is the highest land in southwestern Minnesota, being 1 ,000 feet 

 above the Minnesota river on the northeast, 350 feet above the Big Sioux on the west, and about 

 1960 feet above the sea. For three-fourths of a mile southwest from lake Benton, this channel is 

 double, being divided by a remnant of the morainic range, which rises nearly as high as the 

 enclosing bluffs. The east pass is called the " Dutchman's gap",- and through it the carriage 

 road goes south and then southwest to the " Hole in the Mountain." 



At three other places, eleven, fourteen and eighteen miles northwest from lake Benton (see 

 fig. 49), similar channels have been eroded through the massive ridge of this moraine and through 

 the smooth sheet of drift that slopes downward from its west side. 



The first of these channels begins at the southwest end of lake Shaok- 

 atan, and extends about two miles southwest, in the same course with this 

 lake, through the knolly belt of the moraine, beyond which its course for 

 the next three miles is northwest along its west side, crossing the state line, 

 from section 31, Shaokatan, to the east part of section 21, T. Ill, R. 47. 

 There it is joined from the northeast by the second of these channels, 

 which enters the moraine in the S. W. } of section 7, Shaokatan. This is 

 the only one of these gaps through which drainage now takes place, as at the 

 time of their excavation, from the northeast to the southwest side of the 

 morainic range. Bluffs 7-5 to 100 feet high form the sides of these valleys, 

 of iako enclosing a nearly flat bottomland which varies from twenty to fifty rods 

 dricb. j n w i(jth. Lake Shaokatan outflows northeastward to the Yellow Medi- 

 cine river; but the highest part of the valley that extends from it southwest and then northwest, 

 is only slightly elevated above it. The southwest course of the second channel is continued two 

 and a half miles below their junction, having about the same depth and width to the center of 

 section 30, T. Ill, R. 47, where it enters the last of these remarkable valleys. This lies wholly in 

 Brookings county, Dakota. It extends six miles southward from the southwest end of lake Ilen- 

 dricks, and then, about a half mile beyond the confluence of the valley from lake Shaokatan, it 

 turns west-southwest. Its depth for the first two miles south of lake Hendricks, where its bluffs 

 are capped by the knolls and short ridges of the moraine, is from 150 to 200 feet. Along the 

 remainder of its course to the mouth of the tributary channel, its bluffs ascend steeply about 100 

 feet, and from their top a moderate slope rises 40 to 50 feet higher. Below this junction the val- 

 ley slowly diminishes in depth, and after six miles reaches an area of low land in the northwest 

 part of T. 110, R. 48, which stretches thence to the Big Sioux river. A nearly flat bottomland 

 from thirty to eighty rods wide extends from lake Hendricks the entire length of this valley. Its 

 highest part, one and a half miles from the lake, is some fifteen feet above it, the outlet of this 

 lake being northeastward to the Lac qui Parle river. The channel which has been last described, 

 running south from lake Hendricks, was called by the Sioux "the Brother of the Hole in the 

 Mountain," because of its close likeness to the pass southwest from lake Benton. 



The west ends of lakes Benton and Hendricks, for about a mile of each, are bordered by 

 hillocks and high bluffs, and occupy the extremities of these channels at their entrance with- 

 in the limits of the moraine. Lake Benton is six miles long and from a half mile to one mile 

 wide, its greatest width being at the northeast. Its highest stage of water is four and a half feet 

 above the lowest. This lake is fed by many springs, some of which are ferruginous, along the 

 southwestern half of its shores; and it also appears that springs issue in the bottom of the lake, 

 by which some portions of its surface are kept unfrozen through nearly the entire winter. Bird 

 island, in this lake, is about 25 feet high, and is wooded. At the ordinary low stage of water, it 

 is joined to the north shore by a bar of gravel and sand, several hundred feet long and only from 



vi g . >. Map of the regio 

 jienum, shiwkahm and H 



