w7ce 
 
 /^ ''i>"^ 4&,iSii:a^^ 
 
 Vol. 111. No. 3. 
 
 January , 1907 
 
 MILWAUKEE 
 
 NORMAL SCHOOL 
 
 BULLETIN 
 
 Physiographic Modeli 
 
 of 
 
 Wi 
 
 isconsm 
 
 Published Quarterly by the State Normal School, Milwaukee, Wis. 
 
 F.nteied Jane IS, 1905, at Milwaukee, Wisconsin, at second class matter 
 
 under Act of Congress, July 16, 1894.
 
 This book is DUE on the last date stamped below 
 
 GB 
 
 126 
 
 vr7C2 Case.- 
 
 De script ion of 
 
 Southern Branch 
 of the 
 
 University of California 
 
 Los Angeles 
 
 Form L-1
 
 A DESCRIPTION OF MODELS 
 
 ILLUSTRATING THE 
 
 Physical Geography of Wisconsin 
 
 1 I ,M 
 
 '^-'-■^i '■ 0:' CALiFOBNIA, 
 
 BY 
 E. C. CASE 
 
 MILWAUKEE
 
 A7 
 
 
 ^ 
 
 c 
 
 MODELS SHOWING THE PHYSICAL GEOGRAPHY OF THE 
 STATE OF WISCONSIN. 
 
 These models were constructed in the laboratory of the Depart- 
 ment of Physical Geography and Geology of the State Normal School 
 at Milwaukee. They are based on the last geological map of the 
 state, published in Buckley's "Building Stones of Wisconsin," and 
 have the same horizontal scale — 20 miles to the inch. The vertical 
 scale is exaggerated 100 times, which seems an enormous amount, 
 but is necessary to bring out the features of the eastern part of the 
 state. As only a small portion of the state has been mapped by the 
 topographic survey, a great many of the elevations have been taken 
 from railroad profiles, data given by the first Geological Survey of the 
 state, and by the U. S. Geological Survey. In the preparation of such 
 a small scale model it was impossible to show all parts of the state 
 with any great degree of detail; the attempt has been rather to show 
 the features in a broad way, making rather a "sketch model" than one 
 with pretensions to absolute accuracy. The characteristic features of 
 • ^ different parts of the state have been indicated, as, for instance, the 
 ^ residual mounds of the southwestern portion, the Baraboo Ridge, 
 and the elongated ridges and lowlands on the eastern side of the state. 
 
 The only previous attempt to make a model of the state was by 
 Prof. King, who built a model somewhat larger than the present one, 
 with a smaller vertical scale and on which he attempted to indicate 
 the prominent features. These models are now rather difficult to 
 obtain and are too large for ordinary class room work. 
 
 All of the present models have been prepared on the same base, 
 but have been colored differently to illustrate different features of 
 the state's Physical Geography. The first shows only the Relief; 
 the second shows the state as an Ancient Coastal Plain; the third 
 shows the Glacial Deposits and the Driftless Area. 
 
 The following descriptions of the models are taken largely from 
 Prof. Case's new book, "Wisconsin — Its Geology and Physical Geog- 
 raphy," just issued. 
 
 >^^
 
 THE SIMPLE RELIEF MODEL. 
 
 The state is divided between two slopes; a long and gentle one 
 to the south and a short and more precipitous one to the north. The 
 water parting between these two slopes is very indefinite, for the 
 natural slope of the land is obscured by the overlying drift of the 
 Glacial period, and the highest area of the state, the source of most 
 of the rivers, is fiat and swampy, so that the tributaries of the Mis- 
 sis-sippi and of the St. Lawrence often head in the same swamp. No 
 line can be drawn between the headwaters of the Montreal river and 
 of the Flambeau, a tributary of the Chippewa. 
 
 Fig. 1. Photograph of the Relief Model 
 
 Cut Furnished by the Central Scientific Co., of Cliicago 
 
 The crest of the north slope of the state is about thirty miles 
 south of the shore of Lake Superior, is formed by the summit of the
 
 Penokee and Douglas ranges. In many places the slope is covered 
 by the glacial cla\- so deeply that the underlying rock is not visible, 
 but in other places the portion adjacent to the shore has been washed 
 free from the glacial material and the sandstone stands out in wave- 
 cut bluffs. The rivers running down this slope are slow and sluggish 
 at their headwaters, but as they gain the edge of the slope they plunge 
 down in a series of falls and rapids to the flat land along the shore; 
 near their mouths many of them are again slow. Where they fiow 
 over the soft sandstone they have cut deep gorges almost to the 
 water's edge. Many of the streams have built up large delta deposits 
 at their mouths over which they now wander through swamps and 
 winding channels. 
 
 The southern slope is long and very gentle, extending even into 
 Iowa and Illinois. It is subdivided by a low and irregular divide into 
 two parts; an eastern and a western. The waters of the western 
 slope flow into the Mississippi and so 2,000 miles and more to the Gulf 
 of Mexico; the waters of the eastern slope flow into Lake Michigan 
 and to the St. Lawrence and the North Atfantic ocean, an even 
 greater distance. 
 
 Near the north line of the state is the Penokee Ridge, a long 
 range of low hills which stand up above the surrounding country 
 because their superior hardness has enabled them better to resist the 
 attack of the weather; through the ridge from north to south is cut 
 the Penokee Gap, where the Bad river finds its way from the swampy 
 uplands to the shore of Lake Superior. The Penokee Ridge was 
 formerly called the highest part of the state, but it is now known 
 that the summit of Rib Hill, at Wausau. 1,940 feet above the level of 
 the sea, is higher. 
 
 From the highland of the north central part of the state the 
 rivers run in a distinctly radial manner, giving a splendid illustra- 
 tion of the "consequent" condition. 
 
 South of the highland there is a broad lowland extending across 
 the state in a crescentic shape from east to west. The crescent is 
 broader in the middle and narrows towards either extremity. This 
 is the sandstone area of Wisconsin and it owes its condition as a 
 lowland to the rapid disintegration of the soft sandstone. The pres- 
 ence of this lowland is of the greatest importance to the state, for 
 it is here that all the waters of melting snow and rain enter the 
 ground to appear farther south in the artesian wells for which the 
 state is famous; nor does it cease there, for the artesian wells of the 
 adjacent portions of Iowa and Illinois derive their supply from the 
 same source.
 
 The eastern part of the state is divided between long ridges and 
 lowlands parallel to the shore of Lake Michigan. The westernmost 
 ridge lies along the border of the sandy lowland and separates it from 
 a second lowland to the east in which lies Green Bay, the Lower 
 Fox river, Lake Winnebago, Horicon Marsh, and the Rock river as 
 far south as Watertown. This ridge is low and irregular and is 
 crossed by several streams, notably the Fox and the Wolf rivers. 
 It hardly anoears on the surface as a ridge and might easily be over- 
 looked by one not aware of its presence; the glacial drift lies deep 
 upon its surface and the rocks peep out only occasionally. 
 
 The second lowland, which may well be called the Green Bay 
 Lowland, owes its presence in part to the erosive action of rivers in 
 pre-glacial time and in part to the action of the ice, which sent a 
 long arm down this valley and deepened it and shaped it to its pres- 
 ent form. 
 
 The eastern side of the Green Bay Lowland is formed by the 
 outcrop of a layer of heavy limestone which faces to the west in a 
 steep bluff, but slopes very gently downward to the east. The upper 
 surface of the eastern slope is covered by the glacial debris, so that 
 the rock does not appear on the surface and there is a false appear- 
 ance of abruptness in places; the great terminal moraine of the 
 Green Bay peninsula lies on the gentle slope. On this gentle eastern 
 slope the rivers flow to Lake Michigan; in many cases the accumula- 
 tion of glacial debris causes them to run a considerable distance 
 parallel to the shore before entering the lake. 
 
 The southwestern part of the state is totally different from the 
 eastern, the rocks lie nearly horizontal in the ground, and the rivers 
 in cutting down their channels have not worked the land out into 
 long lowlands and ridges, but have cut straight down through hard 
 and soft alike as they came to it, and the course of the valleys is 
 accidental. This has resulted in deeply incised valleys, which have 
 cut the land up into isolated blocks of land of irregular form. The 
 deep valley of the Wisconsin river cuts off a region of very rough 
 land on the north from a less deeply dissected region on the 
 south. The north edge of the plateau to the south of the Wisconsin 
 river is the celebrated Military Ridge, along which ran the military 
 road west from Madison; it is now occupied almost exactly by the 
 Chicago and North-Western railroad. The most prominent blocks of 
 the dissected plateau south of the Wisconsin river are between the 
 Platte, the Sugar and the Pecatonica rivers. On the summit of these 
 blocks lie the residual mounds, Blue Mounds, Platte Mounds, and the 
 Sinsinnawa mound. These show the height to which the land 
 reached before its degradation.
 
 WISCONSIN AS AN ANCIENT COASTAL PLAIN. 
 
 The second of the models shows Wisconsin as an Ancient Coastal 
 Plain, as described by Prof. W. M. Davis of Harvard. In a broad 
 way the structure of the state is very simple; it consists of a central 
 mass of hard igneous rock formed in the earliest geological period, the 
 Archean. This central mass is surrounded on all sides by layers of more 
 or less horizontal sedimentary rocks, shales, sandstones, limestones. 
 etc. The central mass of hard rocks originally stood up as an island 
 or peninsula in the ocean and the sedimentaries were deposited on 
 the floor of the ocean around the island; they are made up of debris 
 formed by the degradation of this or neighboring islands, in the 
 adjacent parts of Canada, Minnesota and Michigan. 
 
 The edges of all the continents today present a very similar 
 appearance below the water line. They are surrounded by an area of 
 
 imiPii^ 
 
 Fig. 2. PHOTOf.RAPH of Modkl Showinc, Wisconsin as an Anciknt Coastai, Pl.ain 
 Cut Furnished by the Central ScientilTc Co., of ChicaHfo
 
 8 
 
 gradually deepening, shallow water which extends out from the wa- 
 ter's edge for varying distances, but which terminate by a sudden 
 deepening at about the point where the water reaches a depth of 100 
 fathoms (600 feet). The area of shallow water is known as the Con- 
 tinental Shelf, the area of sudden deepening is called the Continental 
 Slope, and the deeper portion of the ocean beyond, of an average 
 depth of two and one-half miles, is referred to as the Oceanic Plateau. 
 The Continental Slope is regarded as the true edge of the continent 
 and the Continental Shelf is potentially a portion of the land, for it 
 is elevated and depressed, geologically speaking, today and tomorrow, 
 and the deposits upon it are the debris of the land. When a portion 
 or all of the Continental Shelf is raised above the surface of the 
 water the flat plain resulting is referred to as a Coastal Plain. 
 
 Upon the Continental Shelf are deposited the sands, clays and 
 limey muds that become the sandstones, shales and limestones of the 
 Coastal Plain when the land is elevated. The deposits from the land 
 rarely reach beyond the edge of the Continental Slielf and the "deeps" 
 of the ocean are rarely raised to the surface to form land, so that 
 there are few rocks that can be recognized as formed of deep water 
 deposits. 
 
 It is in this wise that all the sea coast portion of the eastern 
 tier of states has been formed. The "Atlantic Coastal Plain," lying 
 between the sea and the foot of the Appalachian Mountains, was at 
 one time under shallow water and was built up of the debris from the 
 degradation of the Appalachian Mountains, just as the bottom of the 
 ocean adjacent to the present coast line is receiving deposits today. 
 
 In the alternate elevations and submergences the State of Wiscon- 
 sin went through much the same history as the Atlantic Coastal 
 Plain; the seas surrounding the old Archean land mass were mostly 
 so shallow as to be regarded as a Continental Shelf and on their bot- 
 toms were laid down the debris from the land in the form of clays, 
 sands and calcareous muds which, when the land was elevated, were 
 hardened into the shales, sandstones and limestones of the state. 
 The similarity of the origin and history between the State of Wis- 
 consin and the Atlantic coast is very apparent; only our state passed 
 through its history millions of years ago and the Atlantic coast has 
 still to complete its cycle of development. Wisconsin has very prop- 
 erly been described by Davis as an "Ancient Coastal Plain." 
 
 A Coastal Plain may result from the elevation of the Continental 
 Shelf in two ways. (1) Either it may be raised horizontally upward 
 by a single direct movement of the earth, which will result in a flat 
 expanse made up of horizontal layers of varying hardness; or, (2) it 
 may be lifted by single or successive movements so that its inner
 
 landward end is higher than the outer; this will cause the layers to 
 be tilted in the ground and the edges will appear on the surfaces as 
 successive parallel belts. As soon as the Coastal Plain appears above 
 the surface of the water it is exposed to the degrading forces of nature 
 and the rivers begin to wear down into it. When the strata are tilted 
 the edges of the hard and soft layers come to the surface alternately 
 and the rivers cut down into the soft layers, leaving the harder ones 
 standing up as ridges. The ridges thus formed with one slope short 
 and steep and the other long and gentle are called "Cuesta" ridges. 
 This is exactly what has happened in eastern Wisconsin and explains 
 the presence of the ridges and lowlands. When the rocks are more 
 horizontal the rivers cut straight down and there is an irrcgularitj'' of 
 the topography, as explained above this is the condition of south- 
 western Wisconsin. 
 
 The layers of sedimentary rock which build up the state are 
 from below upwards, the Potsdam sandstone of the Cambrian divi- 
 sion of geological time, the Lower Magnesian limestone, the St. Peter's 
 sandstone, the Galena and Trenton limestones, the Cincinnati shale 
 of Ordovician time, the Clinton iron ore, and the Niagara lime- 
 stone of the Upper Silurian time, and the Hamilton shale of the 
 Devonian time. These show a notable alternation of hard and soft 
 layers. 
 
 Fig. 3. Cro.s.s Section of State from Superior to Milw.^ukee Showing 
 Arrangement of the Strata 
 
 The Potsdam sandstone, the St. Peter's sandstone, the Galena 
 limestone and the Cincinnati shales arc softer, and the Archean 
 crystallines, the Lower Alagnesian, and the Niagara limestone are 
 harder. 
 
 In accordance with the principles of erosion described above the 
 tilted rocks of the eastern portion of the state have been sculptured 
 into long ridges with their steeper faces toward the old land to the 
 north and west and separated by lowlands; the horizontal rocks of the 
 southern part have been sawn apart into isolated blocks. This gen- 
 eral conception of the degradation of the state controlled by the 
 structure of the underlying rock will enable the student to get a 
 better understanding of the details of different portions.
 
 10 
 
 The model shows the surface conditions broadly. The Potsdam 
 sandstone lying directly upon the Archean rocks has yielded rapidly 
 to the degrading forces and has been worked out into a broad low- 
 land over the central portion of the state. The fact that the outcrop 
 of this porous sandstone has been reduced to a lowland and that 
 below the surface it slants away to the south and east below the 
 impervious Lower ^lagnesian limestone, is the important and deter- 
 mining factor in the presence of the artesian waters of the southern 
 part of the state, and of Illinois and Indiana as well. This depressed 
 area is the Inner Lowland of Wisconsin. 
 
 Overlying the soft Potsdam sandstone is the harder Lower Mag- 
 nesian limestone; formerly it extended much farther to the north, but 
 a good portion has been removed in the making of the Inner Low- 
 land. The outcrop of the limestone is a low cuesta ridge with its 
 steeper face to the west and north. It does not show as a bluff on 
 the surface because it is largely obscured by the covering layers of 
 glacial drift, but its course is marked by the presence of a line of 
 gently rising hills from the north side of which the limestone projects 
 at intervals. The course of this ridge is through Marinette, Oconto, 
 Shawano, Outagamie, Winnebago, Green Lake, and Columbia coun- 
 ties. In the last named county the rocks have become nearly hori- 
 zontal, so the rivers no longer recognize it as a determining factor in 
 their course. North of the lower Wisconsin river, in the triangle 
 between it and the La Crosse and Baraboo rivers, the Lower Magne- 
 sian limestone appears capping the tops of hills of horizontal rock, 
 but because of the horizontality the hills are isolated blocks, not 
 continuous ridges. South of the Wisconsin the Lower Magnesian 
 is covered by the rocks of higher formation and is nearly horizontal, 
 but there is a slight dip to the south; this region is a distinct high- 
 land, deeply trenched by the rivers which run over it in an irregular 
 manner, for there is not slope enough to the rocks to determine their 
 course, but on the north the edge of the highland is marked by a 
 steep bluflf which faces to the north and overlooks the Wisconsin 
 river which flows at its foot. The steep face has been formed by the 
 Wisconsin river shifting slowly to the south, following the slight dip 
 of the layers as it wore out its bed in the soft Potsdam sandstone. 
 The crest of this bluff is the celebrated Military Ridge, so called be- 
 cause of the military road that ran along in the early days of the 
 state. It is marked today almost exactly by the course of the Chicago 
 and Xorth-Western railroad from Madison to Dodgeville. This is the 
 inner or first cuesta. 
 
 Overlying the hard rocks of this cuesta are the softer rocks of the 
 Galena limestone an<l the Cincinnati shales. In the eastern part
 
 11 
 
 of the state these have been excavated into a long lowland parallel 
 to the inner cuesta, running through Marinette, Oconto, Outagamie, 
 Calumet, Winnebago, Brown, Fond du Lac, Dodge, Jefferson, Rock 
 and Walworth counties. The course of the lowland is marked very 
 plainly by the position of Green Bay, the Lower Fox river, Lake 
 Winnebago, the Horicon marsh and the Rock river as far south as 
 Watertown. As in the Inner Lowland and the First cuesta the north- 
 ern end where the rocks are most sharply tilted is the most clearly 
 defined. The valley of the Lower Fox river is excavated in the soft 
 Cincinnati shales, so that it has very low walls on the west and the 
 bottom is very broad, but the eastern side is marked by the abrupt 
 cliffs of the steep face of the outer cuesta formed by the overlying 
 Niagara limestone. The whole of the outer, or Green Bay, lowland 
 has the same steep face of limestone from the extremity of Green 
 Bay on the north to a point nearly west of Milwaukee on the south. 
 
 The east shore of Green Bay is formed by a line of bluffs from 
 100 to 200 feet high on the average, but reaching as much as 400 feet 
 in places; these bluffs are nearly vertical and have been sculptured 
 by the weather into peaks and pinnacles, isolated crags and bluffs, 
 that give to the shore a unique beauty. South of Green Bay on the 
 east shore of Lake Winnebago and as far south as Horicon in Dodge 
 county the outcrop of the limestone still forms a ridge though much 
 reduced in height. It is traceable in the local names, Winnebago 
 Ridge and "the ledge." Farther south the lowland area is less appar- 
 ent and the ridge forming its eastern face becomes lower until in the 
 town of Ashippun in Dodge county, about opposite Milwaukee, it dis- 
 appears. The ridge, with its steep western face, is known as the sec- 
 ond or Niagara cuesta; its eastern face is a gentle slope to the shores 
 of Lake Michigan, although the surface appears far from gentle in 
 many places, being covered by the highly irregular superficial deposits 
 of the great terminal moraine. The slope gradually broadens from 
 the northern point of Door county, where the waters of Green Bay 
 and Lake Michigan meet, to the southern edge of the state, where it 
 is about 40 miles wide. 
 
 Far to the west in the Platte and Blue Mounds we have evidence 
 of the former extension of the Niagara limestone over the southern 
 portion of the state, for the tops of these mounds, many feet above 
 the surrounding country, are capped with it and the underlying for- 
 mations show in the sides of the mounds; evidently the rocks of the 
 Niagara period at one time covered all the intervening part of the 
 state and have been removed by the processes of degradation up to 
 the present limits of the cuesta ridge.
 
 12 
 
 THE MODEL REPRESENTING THE GLACIAL CONDITIONS 
 IN WISCONSIN. 
 
 A glacier is any mass of ice, consolidated from accumulated snow, 
 that moves by its own initiation over the ground; usually it is of 
 good size, but many masses of small size clinging to the sides of 
 mountains have a motion which brings them within the definition. 
 The motion is very slow, rarely exceeding a few feet a day (as much 
 as 100 feet a day has been recorded, but this is regarded as highly 
 exceptional). Chamberlin and Salisbury state that the ice cap of 
 Greenland probably does not advance more than one foot a day on 
 the average. The origin of motion in the masses of ice is an un- 
 solved problem, but we know it does move, and moves in a manner 
 comparable to that of a very viscous body. The best analogy is that 
 of a barrel of tar which has been overturned on a warm day; the tar 
 streams slowly from the barrel and drags itself stifily forward over 
 the irregularities of the surface, but eventually accommodates itself 
 to the surface as perfectly as water could and acts upon every inch 
 of the ground. So with the apparently brittle ice; if it is given time 
 it moulds itself in its slow advance to the most intricate irregularities 
 and searches out every exposed surface for its action. Almost every 
 problem of glaciology can be answered, (jualitatively at least, by 
 imagining what would be the action of the flowing mass of tar over 
 the same surface. 
 
 For some reason, probably a combination of elevation of the 
 surface and alteration in the composition of the atmosphere, the 
 climate of the geological period just preceding the present was re- 
 duced so much that great quantities of snow accumulated in several 
 places in the northern hemisphere and slowly spread in all directions 
 from these centers. It is a great mistake to suppose that the ice 
 of the glacial time accumulated at the north pole and spread evenly 
 to the south in all directions; instead the ice accumulated in distinct 
 areas rather far south and spread north as well as east, west and 
 south. In North America there were three such centers, an eastern 
 just east of Hudson's Bay suoporting the Labrador ice sheet, a 
 middle just to the west of Hudson's Bay from which spread the 
 Keewatin sheet, and a western in the mountains about the same lati- 
 tude, supporting a smaller, Cordillcran sheet. It is with the eastern- 
 most of these, the Labrador sheet, that we have most to do, for, with 
 a single and trifling exception it is the only one which entered the 
 limits of the state. 
 
 The advance of the ice over the state was in a manner very 
 different from that usually pictured by students. We have seen that
 
 13 
 
 it did not originate as a single cap at the north pole and advance 
 uniformly to the south over all parts of the earth; neither did it 
 advance with an unbroken front to its farthermost limits and then 
 retreat. Its movement was rather a succession of advances and 
 retreats, no single movement covering exactly the same ground as 
 the others nor having the same extent to the southward. The differ- 
 ent stages of advance have been called invasions and have received 
 
 Fig. 4. Photo(;raph of thk: Model Illustrating the Glacial Conditions 
 
 Cut Furnished by the Central Scientific Co., of Chicago 
 
 names suggested by the states or regions in which they had their 
 maximum development; thus six different invasions have been made 
 out which are called the Alberton, Kansan, Illinoisan, lowan, Early 
 Wiscrmsin and Late Wisconsin. It is the sum of these diflfercnt inva- 
 sions that is spoken of as the Ice Age and the line joining the farther- 
 most cxlt-nl <if LTieh and ail, is spoken of as the southern limit of the
 
 14 
 
 ice. The criteria for distinguishing between two events so closely 
 connected in time as two of these invasions are so obscure, involving 
 the nice balancing of evidence furnished by the appearance of soils, 
 the amount of erosion and the accumulation of vegetable debris that 
 it is often beyond the power of any but the expert to determine the 
 separation. The state was visited by at least two which have left 
 recognizable the traces, an earlier invasion, perhaps the lowan or 
 even the Kansan, and the last, the Wisconsin invasion. 
 
 The forward movement of the ice over the state in the different 
 invasions was not that of an irresistible mass with a straight unbroken 
 front which overwhelmed everything in its path, but rather that of a 
 plastic mass which accommodated itself to the surface and divided 
 to pass around obstacles, doing its work of erosion in the softer rocks 
 and leaving the harder comparatively untouched. In order to under- 
 stand the form taken by the ice the structure and building of the 
 state must be kept clearly in mind; as shown in the first two chapters, 
 it is essentially a core of hard, crystalline rocks, which forms today 
 the highest portion of the state, flanked by successive layers of alter- 
 nately harder and softer rocks, which are so tilted that they outcrop 
 on the surface in successive parallel ridges. Already before the 
 glacial age the softer layers had been excavated by the rivers into 
 lowlands and the harder layers stood up as cuesta ridges. 
 
 Both the earlier and the later sheets were divided into lobes by 
 the irregularities of the ground over which they passed, but the record 
 of the first sheet is much obscured by the deposits from the last one, 
 which passed over much the same territory. 
 
 So far as can be made out the history of the two sheets is some- 
 what similar. The ice of the first invasion advancing in a generally 
 southwest direction from the point of its origin southeast of Hudson's 
 Bay encountered the highlands of hard, igneous rock which form 
 the main portion of northern Wisconsin and the upper peninsula of 
 Michigan and at the same time entered the two great valleys which 
 are now the beds of Lakes Michigan and Superior. As the advancing 
 ice met the barrier of hard rocks, which it could not easily surmount 
 nor remove readily by erosion, it was deflected down the convenient 
 valleys in two great diverging lobes. The western one passed almost 
 directly west through the basin of Lake Superior, probably giving it 
 much of its present shape in its passage, and emerging from the west- 
 ern end turned southwest again, and continued imtil it reached far 
 south of the present southern line of the state. The eastern portion 
 of the divided mass continued almost directly south in the basin of 
 Lake Michigan and when well south of the state spread out to the
 
 15 
 
 west until the edges of the two lobes met in the vicinity of Dubuque. 
 During some portion of the invasion the ice succeeded in passing the 
 highlands to the north and advanced as a short lobe over the central 
 portion of the state as far south as Grand Rapids, approximately. 
 
 The ice of the Wisconsin sheet has left a much clearer record 
 in the form of striations on the rocks, moraines and altered drainage 
 lines. Advancing from the northeast the ice was divided by the same 
 elevated region of hard rocks as was the ice of the first invasion 
 and split into a mass which passed down the Michigan trough and 
 one which headed westward in the Superior trough. These separate 
 masses probably found the guiding lake basins much deeper than 
 did the first ice, for there is no doubt that though the ice felt the 
 guidance of the preglacial topography it shaped and molded the hills 
 and valleys as it passed. 
 
 The large lobe that moved southward in the valley of Lake 
 Michigan was again subdivided into smaller lobes; a larger which con- 
 tinued straight south and is known as the Michigan lobe, and a 
 smaller which moved somewhat to the southwest and is known as the 
 Green Bay lobe. The ice of these two lobes extended down two pre- 
 glacial lowlands, the Michigan lowland on the east and the Green 
 Bay lowland on the west, and that they were divided on the north 
 by the hard rocks of the Niagara cuesta, which projects out between 
 Green Bay and Lake Michigan as the Door peninsula and can be 
 traced farther north in Washington Island, Rock Island, Great Gull 
 Island and a ridge which continues beneath the water and is revealed 
 only by soundings. 
 
 A small lobe extends from the western side of the Michigan lobe, 
 near the southern border of the state; from its relation to the lake 
 of that name it is known as the Delavan lobe. 
 
 The Superior mass spread to west as in the earlier invasion, but 
 the movement of the ice was so great that part of it was forced up 
 the north slope of the highlands and down the other side; as it left 
 the valley of Superior it encountered the hard rocks of the Bay- 
 field peninsula, which divided it into two parts, just as the Door 
 peninsula divided the Michigan lobe, the part to the east extended 
 only a short distance to the south, invading the region which is now 
 about the headwaters of the Chippewa river and has so been called 
 the Chippewa lobe. The western portion of the Superior lobe ex- 
 tended out of the western end of the Superior trough and turned 
 southward as the Superior lobe; it covers portions of Minnesota, 
 Iowa and Illinois, as well as Wisconsin. As in the case of the first 
 invasion, the ^^lichigan and Superior lobes passed around the southern 
 end of the state, and the middle, Chippewa, lobe did not reach far
 
 16 
 
 south of Wausau, so that the southwestern corner of the state has 
 never been touched by the ice, though it is well within the limits of 
 the glaciated portion of the United States; this is the celebrated 
 Driftless Area of Wisconsin. 
 
 Another lobe of glacial ice just touched the borders of the state 
 on the west, in the vicinity of St. Croix Falls, but this one was very 
 different in origin from those which covered most of the state, for it 
 had its birth in the great Keewatin sheet, which developed west of 
 Hudson's Bay and advancing to the south covered the state of Min- 
 nesota, North Dakota and South Dakota. The portion of this sheet, 
 which advanced across Minnesota to the border of Wisconsin, is 
 sometimes called the Minnesota lobe and sometimes the Red River 
 lobe. This lobe of the western ice sheet and the Superior lobe of the 
 eastern sheet met on the line between the states of Wisconsin and 
 Minnesota and have left their recoras in mingled confusion. 
 
 The Terminal INIoraine in Wisconsin is quite generally referred 
 to as the Kettle moraine. As would be expected from its origin, the 
 topography is rough and irregular in the extreme; sharp, steep-sided 
 hills alternate with deep, steep-sided holes which have no outlet and 
 may contain ponds or swamps or be entirely dry. There is no regu- 
 lar arrangement in lines or otherwise of the hills and valleys and the 
 drainage is very imperfect; every feature tells of the violent origin. 
 The deep, steep-sided holes appeared to the first describers to re- 
 semble the large kettles used in the early days in making lye and 
 soap, and so they were referred to as the "Potash kettles" or "kettles" 
 and the name gradually spread to the whole ridge. 
 
 The moraine enters the state from Illinois in Kenosha county, 
 not far from the lake shore, and extends slightly west of north to the 
 vicinity of Burlington, where it turns sharply to the southwest, mark- 
 ing the position of the division of the Michigan glacial lobe called the 
 Delavan lobe; completing the small semicircle in Walworth county 
 around Lakes Geneva and Delavan, which marks the extent of the 
 Delavan lobe, the moraine of the ^Michigan lobe joins that of the 
 Green Bay lobe just north of the village of Richmond, Walworth 
 county,, a few miles south of Whitewater. From the point of union 
 a strong ridge runs northeast across the state almost to the ex- 
 tremity of the Green Bay peninsula. From Richmond the Green Bay 
 moraine runs almost straight north to a point a few miles northeast 
 of Antigo, in Langlade county, where a sharp re-entrant angle marks 
 the union of this moraine with that of the Chippewa lobe. As in the 
 case of the Lake Michigan and Green Bay moraines a ridge runs back 
 northeast from the point of union, marking where the sides of the 
 two lobes met. The terminal moraine of the Chippewa lobe extends
 
 17 
 
 south and west in a great curve through Lincoln and Taylor counties 
 until it meets the moraine of the Superior lobe in Washburn county. 
 Here again a re-entrant angle and a northeasterly projecting ridge 
 marks the meeting of the sides of the two lobes. The moraine of the 
 Superior lobe passes southwest and out of the state in the southwest 
 corner of St. Croix county. 
 
 The origin of the Green Bay and Lake Michigan lobes has already 
 been described and the influence of the preglacial basin of Lake Michi- 
 gan and the Green Bay lowland in directing their course pointed out; 
 but while the main motion of the lobes was to the south they were 
 at the same time expanding in a less degree to the sides, so that the 
 two lobes were overriding the sides of the channels which directed 
 them. As the sides of the lobes advanced in a direction more or less 
 at a right angle to the main motion they gathered in front of them 
 and pushed ahead a terminal moraine in all respects identical in char- 
 acter with the terminal moraine at the front of the lobe; as the two 
 lobes expanded, one to the west from the basin of Lake Michigan 
 and one to the east from the valley of Green Bay, the two sides and 
 the moraines ahead of the sides came together near the middle of the 
 Green Bay peninsula and farther south to the point where the ter- 
 minal moraines meet at Richmond. Because of the origin of this 
 branch of the kettle moraine it has been called an Interlobate mo- 
 raine. As shown above, interlobate moraines also mark the line of 
 meeting of the Green Bay and Chippewa and the Chippewa and Su- 
 perior lobes, but neither of the two is so well marked or preserved 
 as the one in eastern Wisconsin. 
 
 On the western side of the state there is a considerable area be- 
 tween the terminal moraine and the driftless area which is occupied 
 by deposits from the ice of the earliest invasion. There are here all 
 the features of the drift-covered region, but in a much modified form, 
 for they are much older and the forces of degradation have been 
 much longer at work upon them and have reduced them much farther 
 toward the original condition. The shape of this region shows that 
 it was covered by a lobe of the ice very similar to the Chippewa 
 lobe of the last invasion; its terminal moraine leaves the terminal 
 moraine of the last invasion somewhere north of Wausau and runs 
 southwest into Clark county and then curves northwest into Chippewa 
 county and southwest again into Pierce county and so out of the state. 
 A somewhat similar area appears in the extreme southeastern part 
 of the south of the terminal moraine of the Green Bay lobe of the 
 Glacier. 
 
 The Driftless Area. — This lies in the southwestern and western 
 parts of the state and includes narrow strips of the adjacent parts of
 
 18 
 
 the states of Illinois, Iowa and Minnesota. Its northern edge is 
 indented by the convex terminal moraine of the region of earlier 
 drift and on either side of this it sends sharp processes to the north. 
 Its general outline is shown in figure 4. Surrounded on all sides by 
 glaciated country, it furnishes to the student of the state and of 
 glaciology in general a mass of most valuable comparative material, 
 for it shows the topography of an older land in an advanced stage of 
 degradation immediately adjacent to regions which in the latest 
 geological period has been covered by new deposits, now in the ear- 
 liest stages of degradation. It is impossible to even list the theories 
 that have been advanced to explain why this region was not visited 
 by the ice, so that only one, that advanced by Chamberlin and quite 
 generally accepted, will be reproduced here. 
 
 The driftless area lies between the great depression of the Lake 
 Superior basin on the north and that of the Lake Michigan basin on 
 the east, with the highlands, composed of hard, crystalline rocks, 
 directly to the north and northeast. Lake Superior has an average 
 depth of about 1,000 feet; its surface is about 600 feet above the level 
 of the sea; the summit of the highlands 30 to 40 miles to the south 
 is about 1,200 feet above the level of the lake, so there is a difference 
 of about 2,200 feet from the bottom of the lake basin to the top of 
 the highlands. Lake Michigan has an average depth of 900 feet and 
 its surface is nearly on a level with that of Lake Superior, so there is 
 a difference of about 2,100 feet from the bottom of the lake to the 
 summit of the highlands to the west. If the lakes were drained it 
 is seen that the highlands would constitute a very considerable eleva- 
 tion between them with a long slope to the south, including most of 
 the state of Wisconsin and good parts of the rreighboring states of 
 Illinois, Iowa, Missouri and Minnesota. It is probable that the ice 
 advancing from the northeast was split by the hard rocks of the 
 upper peninsula of Michigan and advanced around the highland in 
 the form of lobes which clung to the depressions of the lake basins, 
 but in the forward movement the ice was gradually crowded up and 
 over the obstructing highlands, and in the time of the maximum for- 
 ward movement of the ice crept down the face of the southern 
 slope in what is called the Chippewa lobe. But why, having once 
 surmounted the barrier, did not the ice descend the southern slope 
 as rapidly and as far as the Michigan and Superior lobes? Perhaps 
 for two main reasons. According to Chamberlin the ice surmounted 
 the barrier, 2,100 to 2,200 feet high, only when it was at its greatest 
 advance, and from then on its forward movement was less rapid; 
 moreover, the forward movement of the ice was greatly retarded as 
 it pushed over the hills and was much slower than that of the other
 
 19 
 
 lobes. Again the maximum of forward movement was coincident 
 with the culmination of the Ice age, and thereafter the climate became 
 slowly warmer; the ice, creeping down a long southern slope, was 
 exposed to the full power of the sun and it is probable that the rate 
 of melting was faster there than on the other lobes and faster than 
 the rate of advance. The stronger Superior and Michigan lobes did 
 not waste by melting so rapidly because, instead of being thinned by 
 spreading out, they were more confined in the narrower basins and 
 thickened by accumulation, so that they advanced more rapidly than 
 they were destroyed by melting. It is also probable that the lobes 
 assisted in their own perpetuation, for large masses of snow or ice, 
 by chilling the air which blows upon them, induce an increased pre- 
 cipitation; so these lobes may have chilled the moisture laden air 
 from the south or from the driftless area and caused abundant snow- 
 falls upon their surface. 
 
 Says Chamberlin: "Divided by the Highlands, led away by the 
 valleys, consumed by wastage where weak, self-perpetuated where 
 strong, the fingers of the mer de glace closed around the ancient 
 Jardin of the Upper Mississippi valley, but failed to close upon it." 
 
 These models are made by the Central Scientific Co., of Chicago, 14-28 Michigan 
 street. Information regarding them may be obtained from Mr. Case, or from the 
 
 Central Scientific Company. 
 
 1 i b
 
 iJjs> As iUtLt-S. CALlF.
 
 Lithomount 
 
 Pamphlet 
 
 Binder 
 
 Gaylord Bros. 
 
 Makers 
 
 Syracuse, N. Y. 
 
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