80 LIFE OF THE PLEISTOCENE 



lake level. The cause of this lowering of level was probably the cutting down 

 of the outlet near Lockport. 



At this stage (Plate XXXVII) the shore lines extended from Wilmette 

 southward and southeastward to a point north of Garfield Park, thence south- 

 westward past Hawthorne, joining the Calumet shore line below Lyons. On 

 the south side of the lake the shore line ran parallel with the Calumet beach 

 as far as Palos Springs; from here it extended eastward to Dalton and then 

 formed a long, crescentic beach a mile or two north of the Little Calumet 

 River, and joined the present shore line east of Millers, Indiana. 



Mt. Forest Island was greatly increased in area by the lowering of the water, 

 extending from Summit eastward to within a mile of Englewood, thence south- 

 east to Auburn Park and Pullman, and south to a point a mile or so northwest 

 of Dalton. The island was increased in size on its southern border, Lane's 

 Island became a long and narrow piece of land, and the Sag outlet was reduced 

 to a narrow stream from half a mile to a mile in width. Stony Island appeared 

 above the water at this stage. 



The Rose Hill bar (Plate XXXVIII) was largely built up at this stage to 

 form a wide peninsula extending from Wilmette to Bowmanville, and an off- 

 shore barrier developed, extending from Rose Hill cemetery in a southeasterly 

 direction to North Avenue, at the southern end of Lincoln Park. The enclosed 

 bay was over ten miles in length and from one and a half to three miles in 

 width. The Rose Hill bar was probably largely built up during the interval 

 between the 35 and 20 foot stage, and previous to the formation of the Grace- 

 land barrier. This is made evident by the very strong character of the hook 

 extending from the Rose Hill cemetery thru Bowmanville to the Chicago 

 River. When the water reached the 20 foot level, or perhaps before this time, 

 the Graceland bar was formed, as well as a secondary bar or beach extending 

 from Evanston to Devon Avenue, and thence southward, joining the Grace- 

 land bar. Between this bar and the Rose Hill bar there was a long, very 

 narrow lagoon, which later became a pond. Another pond developed to the 

 north, extending from Church Street northward. The bed of the first long 

 pond can easily be seen west of Clark Street, between this ridge and the higher 

 Rose Hill bar, now known as Ridge Avenue. North of Rogers Park this lake 

 bed is now cultivated by truck gardeners. The contours on the map of the 

 Sanitary District suggest many irregular hooks which usually develop in such 

 situations, where wind and current action are at work in comparatively shallow 

 water. 



a. Comparison with modern embayments 



Wilmette Bay extended from Foster Avenue north to within a short dis- 

 tance south of Central Avenue, Evanston. At this stage it was shallow, the 

 depth ranging from 20 feet at Foster Avenue to 2 feet at the head of the bay 



