132 B. SHIMEK PLEISTOCENE OF SIOUX FALLS AND VICINITY 



On the Iowa side the valley is bordered by hills, which vary in height 

 and niggedness of vertical contours. Xear the northern boimdary of the 

 State and thence to the valley of Bloody Eim they are rather low, and 

 ascend quite gradually to a height scarcely exceeding 150 feet above the 

 valley. South of the creek, and particularly south of the Chicago, Eock 

 Island and Pacific Eailway, the surface is much more l)roken and the 

 bluffs are more abrupt. This rough topography follows the river valley 

 on the Iowa side to Beloit, opposite Canton, and throughout this portion 

 of the territory the rugged hills on the Iowa side rise to a height of from 

 100 to 150 feet above the flat plain, which here extends along the river 

 on the South Dakota side. (See plate 7, figures 1 and 2.) Near the 

 river these ridges are often deeply cut by a bewildering series of narrow 

 ravines, with steep slopes, often more or less wooded, but eastward they 

 gradually merge with the rolling prairie topograph}^, which characterizes 

 the greater part of the surface of Lyon and Sioux counties. Northward 

 this series of ridges and hills is continued along the west side of the Big. 

 Sioux from a point opposite Bloody Eun to the great bend near Sioux 

 Falls, this being the part referred so frequently to the Altamont moraine. 



On the South Dakota side south of this ridge a great plain, gradually 

 sloping to the south and east, extends along the river to a point less than 

 3 miles south of Canton. This plain is in -some places, especially north- 

 ward, cut by narrow valleys or gorges, often to a depth of 50 or 60 feet, 

 but at a little distance these are not visible, and a view of the area leaves 

 the impression of a continuous level plain. The Chicago, Eock Island 

 and Pacific Eailway follows such a narrow valley from the Big Sioux 

 Eiver almost to Shindlar, and many other such valleys may be seen in the 

 same vicinity. Southward the plain is a little lower and these valleys are 

 less prominent, though even this portion of the plain is well drained. 



At several points the level of the plain is interrupted by knobs or 

 ridges, which rise abruptly from the general level. One of these is 

 located near the northeast corner of Canton. Another, much more promi- 

 nent, occupies portions of sections 5, 6, 7, and 8, township 98 north, 

 range 48 west, about two and one-half miles northeast of Canton. (See 

 plate 7, figure 2.) A third is located in sections 19 and 20, township 99 

 north^ range 48 west. These knobs have been regarded as a part of the 

 Altamont moraine, as has been noted. 



South of this Canton plain the rugged, timbered hills extend east and 

 west along the south side of the Big Sioux, the hills on the Iowa side 

 being less abrupt, but at Fairview the line of rough hills again crosses to 

 the Iowa side, though the South Dakota side remains somewhat rough 

 and elevated to a point nearly opposite Westfield, Iowa. 



