CORRELATION OF RAISED BEACHES 421 



S3uth of Port Austin, as is inferred, it is probable that the same is 

 true of the southern half of the Michigan basin, and the Algonquin 

 beach should there be horizontal at the same altitude, 25 feet — the 

 actual position of the highest member of the Toleston group. 



The Nipissing plane can be extended in a similar way and on the 

 basis of somewhat stronger evidence. In the region south of Sturgeon 

 Bay the Nipissing bluffs are developed with remarkable strength, 

 usually 30 and sometimes 80 feet high. The terrace shows an approxi- 

 mately horizontal attitude, descending southward at a very small 

 fraction of a foot per mile, so that at Centerville it stands 14 feet above 

 the lake. South of Centerville, measurements on the Nipissing ter- 

 race at Oostburg (near Sheboygan) south of Belgium, at the state 

 line, at Zion City and Beach Station, 111., place it within a foot or 

 two of 14 feet. It forms a conspicuous bluff which lies just west of 

 the tracks of the Chicago & Northwestern Railway between the state 

 line and Waukegan, 111. In the Chicago district, where no terraces 

 were cut during the lower stages, an extensive series of beach ridges 

 from 10 to 15 feet above Lake Michigan seem to mark the Nipissing 

 and lower planes. Occasionally there is a strong wave-cut bluff, 

 however, in the Chicago district at the 14-foot level, as at Englewood, 

 where the low terrace is the strongest member of the "Tcleston" 

 series. 



The exceptional strength of the Nipissing shore-line and the preva- 

 lence of sharply cut bluffs seem to express the gradual rising of the 

 waters which is known to have led up to this stage in the lake history, 

 according to the studies of Taylor and others. The evidence from 

 Wisconsin and Illinois, therefore, seems to make the Nipissing shore- 

 line horizontal at the altitude of about 14 feet in the southern part of 

 Lake Michigan. Confirming this view is the evidence collected by 

 Lane in Huron County, Alich., where a strong beach that stands 11 to 

 14 feet above Lake Huron is thought to mark the Nipissing plane. '^ 

 A single observation recently made by Mr. Leverett and the present 

 writer a few miles north of Port Huron places a strong beach, prob- 

 ably the Nipissing, at a height of 12 to 14 feet above the lake. Al- 

 though previous observations in Michigan have suggested a slightly 

 lower level for the Nipissing plane, it seems Hkely, all things con- 



I Op. cit., p. 76, and personally communicated to the writer. 



