24 CHICAGO ACADEMV OF SCIENCES. 



125 feet above the lake and the plains from 60 to 90 feet or more. 

 The general elevation is, therefore, higher than in the lake plain 

 bordering the city of Chicago. 



The district between the Des Plaines and Fox Rivers in Lake, 

 northwestern Cook and Dii Page Counties, is largely occupied by 

 the A'^alparaiso moraine. Tliis moraine is interrupted by the 

 Chicago outlet in southwestern Cook and northern Will Counties. 

 East from this outlet it is developed along the watershed between 

 the Kankakee River and Lake Michigan in southern Cook and_ 

 eastern Will Counties and continues thence eastward, swinging 

 gradually to the north around the head of Lake Michigan. 



The 'highest points on the Valparaiso moraine are found in 

 southern Lake and northwestern Cook Counties. One of these, 

 just east of the village of Volo, stands 913 feet, and one in the 

 northwest section of Cook County stands 910 feet above tide, as 

 determined by the Barometric survey under Professor Rolfe. 

 Much of the crest of the moraine in the southwestern part of Lake 

 County rises above 850 feet. In northwestern Lake County and 

 in northwestern Cook County it rises generally above 800 feet 

 and a few points exceed 850 feet. In Du Page County the crest 

 is generally about 750 feet. In AVill County a few points rise above 

 800 feet, but the general elevation is not mucli above 750 feet, 

 and this elevation is maintained eastward about to Valparaiso, 

 Ind., where the moraine rises above 800 feet and continues with 

 an elevation of 800 to 900 feet from that point to the borders of 

 the St. Joseph River in Michigan. 



From the Valparaiso moraine there is less descent toward 

 the Fox River Valley than toward Lake Michigan, the elevation 

 of the immediate border of the valley being 750 to 775 feet in 

 Lake Count}^ and 700 to 750 feet on the borders of Cook and 

 Kane Counties. But upon approaching the Des Plaines River the 

 district outside the moraine becomes about as low as that along 

 the lake, and the immediate valleys of the Des Plaines and Kan- 

 kakee, in Will County, are lower than the lake surface. Farther 

 east the district outside the moraine reaches an elevation higher 

 than the lake level, the altitude of the Kankakee marsh at the 



Explanation of Profile Sections. — The profile sections given 

 in Plate 4 are based upon the railway surveys along six lines radi- 

 ating out from Chicago. The distance to rock is shown by a 

 series of well borings along each line. In cases where rock is not 

 struck the depth of well is indicated. The vertical scale being 

 about thirty times the horizontal, the reliefs of the region are suffi- 

 ciently well outlined to be readily seen. 



