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150 
IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
You are all familiar, by experience or by reputation, with the 
most important Iowa lakes and I need but to mention them to 
recall beautiful memories to your minds. In the eastern moraine 
Clear Lake is without a peer and indeed will bear comparison 
with any in, all the lake region of the central United States. In 
the western moraine, which is much more extensive, the Oko- 
bojis and Spirit Lake hold easy pre-eminence, but a multitude 
of other smaller ones are held in warm regard by their local ad- 
mirers, and certainly lack nothing but size to make them equally 
noteworthy. Storm Lake is deservedly popular among its circle 
of friends. Wall Lake has attained a wide reputation through 
its great wall of bowlders. The Twin Lakes of Calhoun county 
are centers of local attraction, and the same is true of many 
Fig. 13. Pilot Rock, Cherokee county. 
others in the hill country which affords them lodgement, such as 
Tuttle Lake, on the state line in Emmet county, Medium Lake 
near Emmetsburg, Lost Island Lake near Ruthven, and others 
which will occur to your minds. 
Along with their loads of finer material some of the continen- 
tal glaciers brought down from farther north immense bowlders 
which now lie scattered over the surface of the drift sheets. 
Some of these have really enormous dimensions, as for example 
Pilot Rock, a bowlder of Sioux quartzite near Cherokee, which 
