ESKERS OF NORTHWESTERN ILLINOIS. 79 



This esker is situated at the- eastern edge of a basin formed in the 

 Hudson River shales, which is drained by Elkhorn Creek and is known as the 

 Elkhorn Basin. The neighboring districts on the northeast reach an eleva- 

 tion nearly as high as the crest of the esker. A well made on the slope of 

 the esker a short distance west of Hazelhurst shows that the drift at that 

 point extends nearly 100 feet below the base of the ridge and is composed 

 entirely of sand and gravel, but at the village of Hazelhurst rock is reported 

 to be struck in wells at a depth of only 20 feet. 



There are several prominent gravel knolls in the immediate vicinity of 

 the Hazelhurst esker, two of which reach a height of about 100 feet, the 

 others being 20 to 40 feet high. They are situated immediately south of 

 the esker, and are scattered over a width of a mile or more and a length 

 from east to west of more than 2 miles. These knolls are slightly elongated 

 in an east-west direction in several cases, but the two prominent ones are 

 nearly conical. It seems jurobable that they were formed by agencies simi- 

 lar to those which produced the esker — i. e., by glacial drainage — and they 

 are referred to the same esker system. 



Garden piain esker. — In western Whiteside County there is a small esker set- 

 ting in immediately west of the village of Garden Plain, and passing thence 

 westward through the north part of sees. 22 and 21, and terminating on the 

 Mississippi bluff in sec. 20, Garden Plain township. It lies along the south 

 side of the wagon road which leads west from Garden Plain, and in its 

 entire length of 2^ miles does not vary 20 rods from a direct east-west line. 

 The ridge has usually a height of but 5 or 10 feet and a breadth of 20 rods 

 or less. Its structure is exposed only at one place, at a gravel pit in the 

 west part of sec. 22. The beds here bear clear evidence of a westward- 

 flowing stream. The gravel has remarkably fresh appearance, being stained 

 but little more than the usual stain of the Wisconsin eskers, and much less 

 than the stain presented by the gravels in the Hazelhurst and Leaf River 

 eskers. It is barely possible that it was formed at the Iowan stage of gla- 

 ciation, though, as shown below, evidence of the presence of the Iowan ice 

 sheet in this region is far from decisive. The direction of flow of the stream 

 which formed the esker being westward, the ridge can scarcely be referred 

 to a movement of the waters from the lobe of Iowan ice which covered the 

 district to the west of the Mississippi, even if that ice lobe crossed into Illi- 

 nois. It would seem, therefore, that the esker must be referred either to the 



