450 LIFE OF THE PLEISTOCENE 



Plate XVIII. Station 37. East bank of canal. Height of bank IS feet. Photograph 

 by Baker. 



Plate XIX. Stations 33-37. Partly completed excavation looking north toward Devon 

 Avenue bridge, showing one method of excavation. Photograph by Baker. 



Plate XX. Station 43. The stratum of sand and gravel, separating the fossiliferous 

 silt from the clay, is indicated by the arrow. Photograph by Baker. 



Plate XXI. Station 44. The trowel, near top of picture, indicates a deposit of mol- 

 lusks; the rule near the middle of photograph, indicates the position of the sandy clay (stratum 

 iii). Photograph by Baker. 



Plate XXII. Station 45. The trowel indicates the position of the sand and gravel stratum 

 (iv). To the left, above the line, may be seen freshwater mollusks belonging to the genera 

 Galba and Planorbis. Photograph by Baker. 



Plate XXIII. Station 48. Canal looking north toward Church Street bridge. Photo- 

 graph by Baker. 



Plate XXIV. Station 49. There is here no sharp contact between the loamy-silt and 

 the boulder clay. Photograph by Baker. 



Plate XXV. Map of the Calumet-Sag Channel. A cross marks the location of the 

 section described in the text. 



Plate XXVI. Section of Calumet-Sag Channel. The numerals at the right indicate 

 the relative position of the various strata. The height of the section is over 28 feet. Photo- 

 graph by Woodruff. 



Plate XXVII. Portion of section in plate XXVI, shown in greater detail. II, boulder 

 clay; III, boulder pavement and Unio bed; IV, sand and gravel; note the boulders and the 

 cross bedding in one place; V, fine gray sand; VI, clay, sandy in lower part. The sharp 

 demarcation between the clay above and the gravel below is to be especially noted in stratum 

 V. Photograph by Woodruff. 



Plate XXVIII. Diagram illustrating the interpretation of the deposits in section of the 

 Calumet-Sag Channel at 92nd Avenue. 



Plate XXIX. Section of Rose Hill bar (part of the Calumet Beach) at Bowmanville, 

 at the end of the bar as it turns west. Field in foreground was bed of Wilmette Bay. 



Photograph by Woodruff. 



Plate XXX. Diagram illustrating the interpretation of the deposits in the North Shore 

 Channel, between Foster Avenue and Lincoln Avenue. 



Plate XXXI. Map of the Great Lakes region showing early stages of glacial lakes and 

 their outlets into the Mississippi River. The different outlets were not all contemporaneous 

 in time. Lake Jean Nicolet is hypothetical. The map indicates in a striking manner the 

 fact that the repopulation of the territory by aquatic life was by way of the Mississippi River 

 and its large tributaries (compiled from Leverett and Upham; cut from Baker, Mon. Lymn., 

 fig. 3). 



Plate XXXII. The Glen wood stage of Lake Chicago (after Alden). 



Plate XXXIII. The Bowmanville low water stage. 



Plate XXXIV. Wilmette Bay during the Bowmanville low water stage. The numerals 

 on land (593,600, etc.) indicate altitudes above sea level; figures in the bay (5, 10, etc.) 

 indicate probable depths of water. The names and locations of the streets of the City of 

 Chicago in the area studied are given. 



Plate XXXV. The Calumet stage of Lake Chicago (after Alden). 



Plate XXXVI. Wilmette Bay during the Calumet stage. Numerals as in plate 

 XXXIV. 



Plate XXXVII. The Toleston stage of Lake Chicago. The Hammond stage did not 

 differ materially (after Alden). 



