94 YEAKBOOK, PUBLIC MUSEUM, MILWAUKEE. [Vol. I. 



GLACIAL LAKE LAPHAM— A PRELIMINARY 

 ANNOUNCEMENT 



By Ira Edwards"'' 



The broad outlines of the Geology of southeastern Wisconsin 

 were determined by the early researches of Dr. T. C. Chamberlin 

 when he was connected with the Wisconsin Geological Survey of 

 1873-1879, and have been more recently elaborated by Dr. Wm. A. 

 Alden of the United States Geological Survey. These geologists 

 published the results of their work in two large and important pub- 

 lications, and in numerous minor papers. Dr. Chamberlin's account, 

 "The Geology of Eastern Wisconsin," is found in Volume II of the 

 "Geology of Wisconsin" and the conclusions of Dr. Alden were pub- 

 lished as Professional Paper No. 106 of the U. S. Geological Sur- 

 vey series. These publications deal with the indurated Paleozoic 

 rocks, but more especially treat of the Pleistocene, glacial deposits 

 which overlie them. The work of these two men and of others who 

 have from time to time made contributions to the scientific knowl- 

 edge of this region, has, however, left for future investigation, much 

 of the detailed observation necessary to render complete a knowl- 

 edge of the geological history of this State. 



An eflfort to supply some of this needed detail which had been 

 omitted in the broad reconnaissance of the field, led the Depart- 

 ment of Geology to undertake field work in the immediate vicinity 

 of Milwaukee. One of the first fruits of this work is the discovery 

 of traces of a glacial lake, which formerly existed in the valleys of 

 the Menominee and Root rivers. At the present writing, the shores 

 and deposits of this lake have not been completely mapped, but the 

 reconnaissance has been of sufficient extent to demonstrate the 

 existence and to partially determine the extent of this body of 

 water, which is here provisionally given the name. Lake Lapham, in 

 honor of the first scientist of Alilwaukee, Dr. Increase A. Lapham, 

 as was suggested to the writer by Mr. Henry L. Ward, former 

 Director of this Museum. 



It has long been known that the glacial deposits occurring in 

 southeastern Wisconsin were, for the most part, left behind by two 

 lobes of the Wisconsin ice sheet. One of these, the more eastern 

 proceeded down the valley of Lake Michigan, and the other along 



**Curator of Geology, Milwaukee Public Museum. 



