216 Wisconsin Academy of Sciences, Arts, and Letters. 



bly into the drift clay, of the Illinois prairies."^ The members 

 of the geological corps of Illinois did not recognize it distinctively, 

 in the sense in which it is now considered, but Dr. Bannister, in 

 his report on Lake county, says : " In the western part of the 

 county, near the Fox river, we find the ridges, in some places, to 

 be largely composed of rolled limestone boulders. The same 

 character has been observed further south along the same stream 

 and remarked upon in the chapter on Cook county."^ In respect 

 to McHenry county he says : " In the vicinity of the Fox river, 

 the same kind of gravel ridges are met with as those which have 

 been described as occurring in the western part of Lake county." ^ 

 This lies in the belt identified by me, from personal observation, 

 as belonging to the Kettle range. 



Concerning the district farther south, he says : " Boulders of 

 granite, quartzite, greenstone, and various other rocks are abund- 

 ant in various localities on the surface of the ground, and are 

 frequently met with in excavations for wells, etc., and large de- 

 posits of rolled boulders, chiefly of limestone from the under- 

 lying Niagara beds, similar to those already described in the 

 report on Cook county, occur in the drift deposits of the adjoin- 

 ing portions of Kane and Du Page countie?."^ Concerning the 

 topography, the same writer says : " Along some of the prin- 

 cipal streams, and especially the Fox river in Kane county, the 

 country is more roughly broken, and can, in some parts, even be 

 called hilly, although the moiS abrupt elevations seldom exceed 

 eighty or one hundred feet above their immediate base."^ This 

 broken country, if we may judge from what is true of the rough 

 country along the same river to the north of this, it not due so 

 much to the drainage erosion of the river as to the original depo- 

 sition of the drift. The same features are said to continue inta 

 Kendall county, next south, which brings us to the vicinity of 

 the ancient outlet of Lake Michigan, where, of course, the mo- 

 raine is locally swept away. Still farther south, in Livingston 

 county, Mr. H. C. Freeman mentions a ridge running southeast- 



> On Western Boulder Drift. Am. Jour. Sci., Sept., 1869, p. 176. 



=■ Geol. Sur. of in., Vol. IV, p. 130. ■• Geol. Surv. of III., Part IV, p. 113. 



»Loc. cit., p. 131. « Geol. Surv. of IIJ., Part IV, p. 113. 



