CORRELATION OF RAISED BEACHES 419 



the Port Huron outlet were running. The nearly horizontal position 

 of this plane in eastern Wisconsin indicates clearly that very little 

 deformation has occurred there since Nipissing time. 



Below the Nipissing plane are usually several shore-lines which 

 mark more recent stages of the lake, depending upon the deepening 

 and widening of the present outlet. No attempt has been made to 

 reconstruct them; but a 12-foot stage and a 9-foot stage are commonly 

 recorded. These sometimes give rise to confusion regarding the alti- 

 tude of the real Nipissing plane. Near Algoma, for instance, a very 

 strong red-clay bluff of the Nipissing stage has at its base a terrace 

 which is sometimes 12 and sometimes only 9 feet above Lake Michi- 

 gan, but usually about 20, showing that the lake, after dropping a 

 few feet below the 20-foot Nipissing level, easily cut back across the 

 broad terrace to the base of the high Nipissing bluff. 



EXTENSION OF THE ALGONQUIN AND NIPISSING PLANES 

 SOUTH OF TWO RIVERS 



Some difficulty attends the reconstruction of the old water-planes 

 south of Two Rivers, for extensive cliff recession at the Nipissing and 

 the present level has largely obliterated the record. (See Fig. 6.) No 

 trace of a 25-foot beach ridge is seen between Two Rivers and 

 Kenosha. High clay bluffs rise abruptly from the lake to heights above 

 the extinct Algonquin plane, except where for short distances (as at 

 Centerville, between Sheboygan and Port Washington, and at Fox 

 Point) a terrace and bluff of the Nipissing stage has cut farther back in- 

 to the upland. In inost of the stream valleys along this distance there 

 are terraces which mark the adjustment of streams to two and some- 

 times more high stages of the lake, their heights corresponding closely 

 to the Algonquin and Nipissing planes. At Kenosha there are short 

 remnants of a 25-foot beach ridge, and at Evanston, 111., a strong 

 beach ridge of the "Toleston" group of beaches of Lake Chicago runs 

 inland at the height of 24 feet, and may be followed with occasional 

 interruption through the Chicago district and around the head of 

 Lake Michigan. 



The flattening of the highest Algonquin plane in eastern Wisconsin, 

 going southward toward Two Rivers, strongly suggests that it there 

 becomes essentially horizontal. The presence of a very definite beach 



