SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1928 MOHAINES AND SHOHE LINES OF THE LAKE SUPERIOH BASIN By FR A.NK LEVERETT INTRODUCTION WORK BY ASSISTANTS SCOPE OF THE REPORT The assistants were furnished by the Michigan Geo­ logical Survey durjng part of the work in that State. The district discussed in this report embraces the Although they did very little independent work on entire northern peninsula of Michigan and the parts of the surface geology, they were very helpful in run­ northern Wisconsin and northeastern Minnesota that ning out side lines and filling in intervals between were covered by a readvance of the Superior-lobe of traverses made by the writer, as well as by their com­ the Labrador ice sheet late in the Wisconsin stage of panionship in breaking courses through the woods in glaciation. Part of the northern peninsula of Michi­ unsettled or very thinly inhabited parts of the district. gan is outside the linlits of the Lake Superior drainage G. E. Tower, a student of the University of Michi­ basin, but the Superior lobe passed over it in this read­ gan, and W. C. Gordon, of the l\1ichigan Geological vance to reach the basins of Lake Michigan and Lake Survey, assisted in 1905; L. H. Wood, of the Western IIuron. There is, however, a slnall area in Iron County Normal School of Michigan, in 1908; 1. D. Scott, of nnd southeastern Gogebic County, Mich., which was the geological department of the 'University of Michi­ not overridden by the readvancing Superior lobe. gan, in 1910; L. G. Hornby, university student, in This area is included in the present report in order to 1912; and R. W. Peterson, of the Michigan Agricul­ bring out the contrast between its features and those tural College, in 1919. In the Minnesota work assist­ produced by the. Superior lobe at the later time. A ance was furnished by the State Geological Survey, sinlilar comparison is also made between the glacial connected with the University of Minnesot.a. This features of the Superior lobe in northern Wisconsin included the services of A. H. Elftman for a few days and northeastern Minnesota and those imnlediately in 1913 and a considerable part of the services of F. 'V. outside the lnnits of the readvance. Sardeson for a period of years. -The eA1>enses of the TIME GIVEN TO THE INVESTIGATION work by Doctor Sardeson prior to 1912 were met by the United States Geological Survey. The Wiscon­ The studies on whieh this report is based began in sin Geological Survey contributed the services of F. T. the field season of 1905, during which three or four Thwaites and an assistant in running levels to high counties in the east end of the northern peninsula of shore lines at Bayfield and on Oak Island. Some of Michigan were examined. No further work was done the writer's work in Wisconsin was done in company in this district until 1909, .when studies were made with Samuel Weidman, of the Wisconsin Geological along the inunediate border of Lake Superior in Mich­ Survey, who was' making investigations preparatory igan and to some extent in Wisconsin and Minnesota. to a general report of his own on northern Wisconsin This work was continued in 1910 and 1911, so that for the State survey. , ncarly the entire district had been examined by the end of the 1911 field season. In 1912 -about three NATURE OF COUNTRY AND CHARACTER OF'INVESTIGATION wecks was spent in running levels to shore lines in t~e The present report on the glacial and lake features of northern peninsula, and in each of three subsequent the Lake Superior Basin is made as a report of progress years-1913, 1914, and 1916-this district received rather than of a completed study. Owing to the three or four weeks' attention in connection with other imperfect development of roads or line~ of travel, the studies in Minnesota. In 1919 about five weeks sparseness of settlement, and the uncleared and brushy was spent in Menominee County, Mich., and a num­ condition of much of the land bordering this basin, it ber of places farther east, including Drummond Island. was found to be impracticable to work in the detail The entire time taken in field work in the several years that is done in more fully -cleared and well-settled amounts to about 16Y2 months by the writer and districts. As a consequence there has been very little about 6 months by his assistants. consecutive tracing of the courses of shore lines and of 1 2 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY I 1928 other features that need close work for complete in Monograph 38 and those of southeastern Wisconsin mapping. The entire set of beaches has been crossed by W. C. Alden in Professional Paper 106. There is along a number of lines leading from the shore of Lake also lacking an adequate study and treatment of the Superior up to the limits of lake action, but these Ontario Basin, the Georgian Bay Basin, and the traverses have only served to show that the develop­ nortpern part. of the Superior Basin-much of whi~h ment of beaches was not at all uniform, there being a falls to the Canadian geologists. larger number of definite beaches on certain lines of traverse than were found on neighboring lines. It EARLY EXPLORATIONS AND INVESTIGATIONS has thus become apparent that a complete correlation of beaches can be made only by detailed work that will The Lake Superior shores were visited by mission­ aries, explorers, and traders as early as the second entail much more time and expense than it has seemed half of the seventeenth century, or fully 250 years best to allot to the study of the region at present. The ago. A map of Lake Superior coast line published extent of lake action has been determined with close in Paris in 1672 shows that most of the shore had approximation, however, and a large amount of been explored by persons skilled in observation and information concerning the tilting of shore lines has mapping. This map is reproduced in the Foster and been collected. The direction of the melting away Whitney report on the Lake Superior land district of the border of the ice sheet has been somewhat fully published in 1850. An interesting compilation of worked out, and the relation of the lake stages to the journals of these early explorations, by Louise Phelps ice has been determined to some extent. There are, Kellogg, entitled "Early narratives of the Northwest, however, a few matters of uncertainty as to the cor­ 1634-1699," was published by the Scribners in 1917. relation of some of the moraines with shore lines that Over a century ago, in 1820, Henry R. Schoolcraft it has been found difficult to clear up, and for these a conducted a scientific expedition to the upper Great tentative correlation is the best that can now be given. Lakes, giving attention to their shore features as well RESTRICTION TO LATE PART OF GLACIAL EPOCH as the mineral formations. He noticed evidence of lake action at high levels in the form of both shore This region has experienced not only repetition of lines and lake deposits. These features were also glaciation from one direction but also a marked shifting noted by the British traveler Dr. John Bigsby at an of ice movement in the last glacial stage, so that trans­ even earlier date, his observations having begun in portation of glacial debris and striation of rock ledges 1817 and his papers being published in 1821. A paper are far from uniform in direction. Thus at times the by H. W. Bayfield outlining the geology of. the Lake ice passed southward across the west end of the Lake Superior basins appeared in 1829. A report by Dou­ Superior Basin with a surprising disregard of the topog­ glass Houghton on the copper of the Lake Superior raphy, whereas at other times the ice movement was Basin appeared in 1834, and his offical· reports as markedly controlled by the topography, and the axial State geologist of the First Geological Survey of direction was through the basin from its northeast to Michigan for 1840, 1841, and 1842 deal to some its southwest end. The present report deals almost extent with the northern peninsula. After the dis­ entirely with the latest ice movement that affected continuance of this geological survey arrangements the Lake Superior Basin. The disappearance of the were made by Houghton with the United States ice from this basin occurred very late in the Wisconsin General Land Office to combine a geological survey stage of glaciation. Indeed, this basin seems to have with the linear land survey in the northern peninsula. been about the latest part of the northeastern quarter This work, which began in 1845, was terminated of the United States to lose its ice covering. near the end of the first field season by the drowning This report supplements Monograph 53 by carrying of Houghton in Lake Superior in October, 1845. His the description from the north end of the Huron and notes and maps, however, were brought out the fol­ Michigan Basins to the west end of the area of the great lowing year by Bela Hubbard, and with them the Laurentian lakes. Taken in connection with that notes of William A. Burt, an engineer in the land monograph, it sets forth how the ice front made its survey. The township plots made in the survey final retreat and how ponded waters were formed in carry numerous notes on the geology and topography.