ILLUSTRATIONS 



Page. 



Plate I. Map showing the several drift sheets and the present glaciation of North America. 2 

 II. Map showing base lines and principal meridians in the district covered by the 



Illinois glacial lobe . 4 



III. Topographic map of Illinois and western Indiana Q 



IV Map showing areas between 100-foot contours _ s 



V. Profiles across Lake Michigan 12 



VI. Glacial map of Illinois ice lobe 24 



VII. Bowlder bed at Keokuk, Iowa . 04 



VIII. Glacial map of southwestern Indiana % 



IX. Glacial map of south-central Indiana 102 



X. A, Sangamon soil, near view; B, Sangamon soil, more distant view 126 



XI. A, Exposure on Farm Creek, near Peoria; IS, exposure on railroad cutting east 



of Peoria . 128 



XII. Glacial map of northwestern Illinois 130 



XIII. Exposure of Wisconsin gravel 274 



XIV. Glacial map of parts of Kane and Kendall counties. Illinois 284 



XV. Glacial map of southwestern Michigan 340 



XVI. Striation of under surface of limestone 41g 



XVII. Map of Lake Chicago area 420 



XVIII. Topographic map showing drainage features near Fulton, Illinois, and in vicinity 



of the upper rapids of the Mississippi In pocket. 



XIX. Topographic map showing drainage features near Ottawa, Illinois 508 



XX. Map of Illinois, showing distribution of wells _ 544 



XXI. Geologic map of Illinois and western Indiana 552 



XXII. Map showing main absorbing areas for the Potsdam and St. Peters formations .. 556 



XXIII. Map showing distribution of artesian wells and deep boriugs 556 



XXIV. Map showing the relation of the drift to ordinary wells 556 



Fig. 1. Section of Silveria formation near Freeport, Illinois 112 



2. Glaciated surface in bed of Chicago drainage canal 416 



3. Grooves exposed in bed of Chicago drainage canal _ 417 



4. Sketch map of the region bordering the lower rapids of the Mississippi River 468 



5. Section from Sonora, Illinois, to Argyle, Iowa 469 



6. Sections across Rock River Valley, in northern Illinois 488 



7. Section from the Wisconsin River, in Grant County, Wisconsin, southward to Cap au 



Gres, near the mouth of the Illinois 554 



8. Section from Galena to Olney, Illinois 554 



9. Section from Davenport, Iowa, to Joliet, Illinois 554 



XIII 



