464 



JAMES WALTER GOLDTHWAIT 



38, and 23 feet above Lake Michigan, or approximately 636, 619, and 

 604 feet above sea level. In the following table, the altitudes of 

 these beaches is given for six selected localities, where spirit-level 

 measurements have been made by the writer. 



It will be noticed that the first four locahties are on the west side 

 of Lake Michigan. The last two are on the east side. Spring Lake 

 and Eastmanville are near Grand Haven. The symbol "x" in the 

 table indicates that the shore line is missing because of destructive 

 cliff cutting at a lower stage. Other measurements might be given, 

 less accurate than these, but confirming them, almost without excep- 

 tion. They indicate that as far north as a line through Grand Haven, 

 Mich., and Milwaukee, Wis., the three beaches of Lake Chicago are 

 horizontal. The terrace at Eastmanville, given at 613' in the table 

 above, is so obscure a feature that its exact altitude cannot be esti- 

 mated within several feet. Disregarding this one measurement, then^ 

 the data show a remarkable accordance in the altitude of beaches, the 

 variation being not more than five feet for each stage. That much 

 ariation, as has already been remarked, must be expected in the 

 original construction of the beaches. There is no indication of 

 system in the slight departures from uniformity of height from north 

 to south, hence no reason to suppose that any of these water planes 

 are inclined at all south of Grand Haven and Milwaukee. Appar- 

 ently, then, these beaches, representing the earliest stages of the 

 lakes of late glacial times have been unaffected by any of the earth 

 movements which are known to have deformed the central and 

 northern portions of the Great Lake region since the ice withdrew. 



On the accompanying map (Fig. i) the northern hmit of hori- 

 zontality for these beaches of Lake Chicago is indicated by a line;^ 



