KANKAKEE AND IROQUOIS COUNTIES. 227 



toms are large deposits of sand ; and sand ridges from fifteen to thirty feet high, 

 form, in many places, the boundaries of the bottoms, that is, the banks of the 

 ancient river valley. Similar banks were traced up the valley of the Iroquois, 

 as far as Middleport, in Iroquois county, and are said to form its banks for 

 some miles above the Indiana line. These banks were not carefully examined, 

 for want of time, but I learn that they contain, in many places, numerous 

 shells of Unio, Paludina, and other forms, identical with those now living in the 

 rivers. 



I was formerly inclined to believe that the Kankakee valley was at one time 

 occupied by an outlet of Lake Michigan, which ran from its southern extremity 

 by the valley of either Deep river or Salt creek; but, since I find that the 

 sand ridges are continuous with those which are so largely developed in the 

 upper part of the Kankakee valley, and especially since Dr. E. Andrews, the 

 learned President of the Chicago Academy of Science, assures me, from per- 

 sonal observation, that no connection ever existed by Deep river or Salt creek 

 valley, I am compelled to believe that this was a distinct lake basin, twenty- 

 five or thirty miles wide in its upper part, and of as yet undetermined length 

 The sand ridges, which mark its outlines, have been traced, almost continu- 

 ously, from the mouth of Waupecan creek, on the south bank of the Illinois, 

 nearly opposite Morris, in Grundy county, to the mouth of Yellow river, in 

 Starke county, Indiana. I learn from Mr. A. J. Matthewson, of Lockport, 

 who has explored much of the Kankakee valley, that they continue over the 

 divide, and connect with the sand ridges of the Wabash valley. This, how- 

 ever, unless the connecting portions are proved to have been deposited by water 

 in their present position, would not prove the connection of the waters of the 

 two basins, since the wind often raises, upon lake shores, accumulations of sand 

 to a considerable hight above the water level, as at Michigan City, where an 

 elevation of this sort has attained a hight of one hundred and seventy-six feet 

 above the lake ; and these connecting portions may have had that origin. 



Along the Louisville, New Albany and Chicago railroad, the highest sand 

 beds on the south side of the valley were found at forty-five miles from Michi- 

 gan City, at an elevation of twenty-five feet above the Kankakee, and one hun- 

 dred and four feet above Lake Michigan. On the north side of the valley, 

 the highest beds were found at Hog creek, twenty-one miles from Lake Michi- 

 gan, at about the same level. Above this level, at both points, the gravel beds 

 of the Drift come to the surface, covered only by the soil. Through the east- 

 ern part of Iroquois county, Illinois, and the central part of Benton county, 

 Indiana, there is said to be a stream of boulders, two miles wide, having a gen- 

 eral northwest and southeast direction. Although these must have been 

 dropped from floating ice, at a time when all this country was under water, so 



