84 A NATURALIST IN THE GREAT LAKES REGION 



spit thrust out from the north end of the large island, its elbow 

 at what is now Summit, sheltering a big bay then probably an 

 extensive marsh. 





FIG. 52. Lake Algonquin; some water was still going out of the Chicago 

 outlet but most of it discharged down the. Trent River Valley to Champlain Sea. 

 Note also the Hudson and Mohawk estuaries. This represents about the Tolleston 

 stage. After Leverett and Taylor. 



Jefferson Park, Cragin, Riverside, Summit, Washington 

 Heights, Oaklawn, Dal ton, Thornton, etc., are all on the old 

 Calumet beach. Eastward it follows closely the Glenwood shore 

 line to which it is roughly parallel. There was a great offshore 

 bar built up at this stage. This now terminates near Rose Hill 



