xiv LIST OF ILLUSTRATIONS 



PAGE 



FIG. 25. A Dyke near Marquette, Michigan 39 



FIG. 26. A Monadnock, Ishpeming, Michigan 40 



FIG. 27. Rocks Folded and Crumpled, Jasper and Hematite, 



Ishpeming, Michigan 41 



FIG. 28. Map of Surface Rocks, Illinois, Wisconsin, Michigan . 43 

 FIG. 29. A Coral Reef Exposed at Quarry, Thornton, Illinois, 



Showing the Concentric Lines of Deposit ... 45 

 FIG. 30. Map Showing Land and Sea When Potsdam Sandstone 



Was Depositing (Upper Acadian), after Schuchert . 47 

 FIG. 31. Map Showing Land and Sea When Magnesian Limestone 



Was Depositing (Beekmantown), after Schuchert ... 47 

 FIG. 32. Map Showing Land and Sea When Richmond Shales Were 



Depositing (Cincinnatian), after Schuchert . . . 47 

 FIG. 33. Map Showing Land and Sea When a Part of the Niagara 



Limestone Was Depositing (Mid-Silurian), after 



Schuchert / . .47 



FIG. 34. Animal Fossils from Niagara Limestone . . . . 49 

 FIG. 35. Map of the Late Paleozoic When the Illinois Coal Beds 



Were Depositing (Upper Pennsylvanian) , after Schuchert 5 1 

 FIG. 36. Fossils of the Coal Period from Mazon Creek, Illinois . 53 

 FIG. 37. The Great Arch of Rocks in Illinois, a Diagram r . . 54 



CHAPTER IV 



FIG. 38. Glacial Map of North America > V ..- -v^ ;j : /i' .' . . 57 



FIG. 39. Conjectural Preglacial River System . . ... 58 

 FIG. 40. Angular and Striated Glacial Bowlder near Glencoe, 



Illinois .,, ; ; ., ; > .,,.,;, ,, }C > ,,r>; >$?$*&&% / . 6o 

 FIG. 41. Grooves and Scratches on Bed Rock at Stony Island Due 



to Glacial Erosion . .. >.' .'..,,;, - ; y - % ; . . 61 



FIG. 42. Map of Moraines in the Chicago Region . . ; . . 62 

 FIG. 43. Map of Moraines in Illinois, from Bulletin State Geological 



Survey . . .'. . .. ' ... .... . 65 



FIG. 44. View of Typical Glacial Country a Few Miles Southwest 



of Chicago . . L , . . . . . . . . 66 



FIG. 45. Flathead, below Joliet, General View and Detail . . 67 



FIG. 46. Figures of Several Crystals 68 



FIG. 47. Cleavage Shown in a Piece of Octhoclase Feldspar * . . 69 



CHAPTER V 



FIG. 48. The Wisconsin Ice Sheet at Its Maximum Extension ' . 79 

 FIG. 49. An Old Shore Line of Lake Chicago 80 



