Clark County, Wisconsin - Chapter 2: Physical Features., 1918

Clark County is located in the west-central part of Wisconsin, and is bounded on the north by Taylor County, on the east by Marathon and Wood counties, on the south by Jackson County, and on the west by Chippewa, Eau Claire and Jackson counties. It is thirty miles from east to west, and forty-two miles from north to south, embracing Townships 23, 24, 25, 26, 27, 28 and 29 north, of Range 1 east, and 1, 2, 3 and 4 west of the Fifth Principal Meridian, with the exception of Township 23, Range 4 west. The area of the county is 1,200 square miles, as compared with a state area of 54,450 square miles. Only seven counties in the state, Bayfield, Douglas, Forest, Marathon, Marinette, Price and Sawyer have larger areas.

The mean annual temperature ranges from 42 degrees in the southern part to 44 in the northern part. The annual rainfall ranges from 36 inches in the southern part to 44 in the northern part.

The county is in the Mississippi Valley, and is drained by three of the river systems of that great waterway. The Black River, running south, through a well defined valley, nearly divides the county. Its principal tributaries from the east in this county are the East Fork and Cunningham, O'Neill, Cawley and Rock Creeks, Its only important western branch in this county is Wedge's Creek, of which Five-Mile Creek is an important branch. Branches of the Eau Claire River, a tributary of the Chippewa system, drain the western part, while branches of the Yellow and Eau Pleine rivers of the Wisconsin system, drain the eastern part. The Black River, for nearly its entire course through the county, is one continuous succession of rapids, with a fall averaging for over forty miles fully 15 feet to the mile. This power is susceptible of improvement at almost any point, the bed of the stream and its banks being rocky, and the soil of such compact nature as to render the building of dams feasible and comparatively easy.

The surface of the county is for the most part gently undulating, and at the coming of the whites, was divided into timberland, swamps and prairies, the former predominating. About Neillsville, and to the due eastward, along the moraine, the country may be described as rolling, rather than undulating, but north of the moraine the land is nearly level.

The soil is admirably adapted to certain phases of agriculture, especially for grazing, hay being the predominating crop, oats the next, and barley, corn, potatoes, rye and wheat in the order named.

Throughout the greater part of Clark County, Potsdam Sandstone of the Cambrian period is the surface rock, The Pre-Cambrian crystalline rocks which, in this region underlie the Potsdam Sandstone, are to be observed in several places in the county. Crystalline rocks, largely granite, lie along the northern and eastern boundaries of the county. Other crystal- line rocks, largely granite, gneiss and schist, with here and there a small outcropping of diorite-gabbro, are exposed along the Black River from Hemlock, south to the southern boundary, along Black Creek, Cunningham Creek and O'Neill Creek, and in isolated spots in a general eastern and northeastern direction from Neillsville to the eastern county line. These formations present few features of distinctive interest.

The county owes the general character of its surface to glacial action. Three distinct stages of the "older drift," so-called, are represented here. This older drift was laid down by three separate ice sheets, and for convenience students have designated the three older drift deposits as the First, Second and Third drifts. The First drift area covers the southern and southwestern part of Clark County. The Third drift area covers the northern part of Clark County. The second drift area covers the central and western part of the county. The terminal moraine, or border, of the Wisconsin, or newer and latest glacial drift, touches the northern part of Thorp. The border of the driftless area, that is the region which shows no glacial deposits, crosses the southwestern corners of Mentor and Dewhurst. Alluvial deposits cover several sections in Dewhurst and Levis, extending up the valley of the Black River, but spreading far east and west on the southern boundaries of these townships.

The area of the First sheet of the older drift will be considered first. This sheet covers the southern and southwestern part of the county. The southern border, or terminal moraine of this First drift sheet, that is, the border between the First drift sheet and the Driftless Area, already mentioned, can be traced across the southwestern corner of Clark County from the vicinity of the mouth of the East Fork of the Black River, in a northwest direction to the northwest corner of the town of Dewhurst, crossing the Neillsville branch of the Chicago, St. Paul, Minneapolis & Omaha Railroad, about five miles northeast of Merrillan, and crossing the main line of the same railroad about five miles northwest of Merrillan. About two miles southeast of Humbird there are a few sandstone ridges covered with drift, and a variable amount of coarse bouldery drift has been observed along the wagon road leading northeast to Neillsville. A mile or so west of Humbird, however, coarse erystalline boulders are rare, and upon the slopes and summits of the uplands is a mantle of loess or loam deposit like that prevailing in the region of the southwestern part of the state. This loess is a later formation than the First drift, and has not been found to extend as far east as Clark County.

The First drift, back of its border, between the border and the next overlying drift-sheet - the Second in Clark County - presents no features of special interest. The drift is quite generally present upon the summits of the upland areas, but along the valley slopes and in most of the smaller stream bottoms, the underlying indurated rocks prevail.

In the region where the Potsdam sandstone is the prevailing underlying rock, considerable areas are almost wholly devoid of drift. That portion of Clark County, the southern and southwestern part, covered by this drift formation, is largely within the sandstone district, the erystalline formation occurring for the most part only along the beds of the streams.

The drift, therefore, is a sandy formation, and clayey drift containing abundant crystalline boulders is the exception in this part of the area. The sandstone becomes very abundant in the western part of the county, where numerous hills of sandstone dot the rolling plain.

In the southern part of the county there are a number of drift covered ridges, among which may be mentioned the group in the northern part of Section 8, Township 23, Range 1 East, and single ridges in the southern part of Section 12, in the northwestern part of Section 14, and in the southeastern part of Section 27, in Township 23, Range 2 West.

West of the Black River the area of this formation is mainly sandy land, and the country is opened but very little to agriculture. But little of this part of the county has been traversed by the geological observers outside of the railroads and two or three wagon roads crossing it. So far as could be observed the drift was seen to have a thickness of fifteen to twenty feet in but comparatively few places. Throughout there is a plentiful seattering of coarse crystalline boulders over the surface. On the whole, however, the drift covering southwestern Clark County is relatively very thin, though in the Northwest 1, of Section 14, Township 27, Range 4 West, a large drift ridge shows a thickness of forty-two feet of drift. Along the railroad between Greenwood and Fairchild, drift is shown abundantly along the track as a veneer to many of the low sandstone hills. Upon the tops of the high mounds, such as South Mound, in Section 2, Township 26, Range 3 West, no drift can be found. But if an estimate is to be made of the average belt of terminal moraine or border of the First drift, a fair approximation would appear to be about fifteen to thirty feet in this county. The thickness back of the terminal moraine is probably less than five or six feet.

The Second drift, as stated, covers the middle and eastern portions of Clark County. Its southern border, that is the terminal moraine which represents the edge of the ice sheet which laid down this Second drift, forms a broad curving ridge upon which the cities of Neillsville and Marshfield are located. This ridge has been followed by investigators for a distance of about seven miles across southwestern Marathon, northwestern Wood, and through Clark County. Its continuation to the northwest has been located in the adjacent area of Chippewa County, where it disappears beneath the late drift of the Wisconsin epoch just east of the Chippewa River, Its continuation to the north of Marshfield, across Clark County into Taylor County, is less definite.

This moraine extends across northwestern Marathon, northwestern Wood, and through Clark County in such a manner as to form a broad letter "U," the base of the "U" being directed toward the southeast and the arms spreading outward to the north and northwest.

This terminal moraine may be conveniently referred to as the Marshfield moraine or the Marshfield-Neillsville moraine, since it has, perhaps its most pronounced development in the immediate vicinities of Marshfield and Neillsville and between these cities.

The Marshfield moraine, as noted, forms a broad curve, upon which are located, besides the cities of Marshfield and Neillsville, the villages of Bakersville, Lynn and Granton. Throughout its course from Marshfield to Neillsville it stands out as a broad ridge from 75 to 150 feet above the surrounding lower land to the south and southeast, and from the south it can be seen for a distance of ten to twenty miles. From the northwest, in the region of thicker drift back of this moraine, it appears less pronounced, but still is a distinct topographic feature of the landscape. This moraine is nowhere a sharp ridge, but is broad, with gently sweeping slopes. The base of the moraine is generally from one to three miles wide, and the summit from one-half to two miles wide. The moraine does not possess the abrupt forms of recent glacial topography, but quite generally exemplifies of long continued erosion of the drift by streams and rains.

Both slopes of the moraine are gentle, with the outer slope to the south in general somewhat less gentle than the inner slope. The steeper outer slopes are pronounced in the vicinity of Marshfield and Lynn. At Neillsville, the O'Neill Creek is cutting against the inner side of the moraine, which probably explains the less gentle slope of the north side of the moraine at this place.

Numerous wells upon the slopes and summits of the moraine reveal thicknesses of drift varying from 60 to 170 feet. The ground water level is approximately at the base of the moraine at the level of the streams in this vicinity, and hence nearly all of the wells penetrate to the bottom of the moraine in their respective localities. But there are benches of considerable extent where good water is obtained in the drift many feet above the underlying crystalline rock level, several good wells about Neillsville not being over forty feet deep. At Marshfield the maximum known depth of the drift is eighty-seven feet, about three miles north of Lindsay, 160 feet, and in the vicinity of Neillsville there are several wells from 120 to 160 feet which do not reach the crystalline rocks.

A mile west of Neillsville the morainic ridge turns to the north, extending northward along the Black River as far as Greenwood, and thence to the northwest, entering the southeast corner of Chippewa County. The bend in the moraine west of Neillsville stands out sharply when seen from the south and west. Along the Black River the erosion of the river has greatly modified the moraine, yet it stands out prominently when seen from the west. The marked difference in the rich soil conditions of the moraine as compared with the light soils of the thin First drift overlying the sandstone farther west is a pronounced characteristic of this part of the country. The moraine and the thick drift to the east is laid out into thriving farms, while to the west the sandy land has been avoided by the farmer.

For some distance northwest of Greenwood the moraine lies in a thickly wooded country and cannot well be defined, but southwest of Thorpe, and south of Stanley, in Chippewa County, farms have been developed upon it, and it is seen to stand out in marked contrast to the flat sandy land to the south. Its lack of prominence in this locality is probably due to removal by erosion. It has.been traced across southeastern

Chippewa County, and is found to be crossed by the Yellow River a short distance west of Cadott and passes beneath the terminal moraine of the Wisconsin formation just east of the Chippewa River.

At Marshfield, as at Neillsville, the moraine makes a sharp turn to the north. The moraine stands out as a distinct flat-topped rise of land as far north as McMillan, where it is crossed by the Little Eau Pleine River. Along the road between Sections 28 and 29 of Township 26, Range 3 East, wells show thicknesses of 90, 106, 108 and 120 feet of drift, A mile or so farther northeast the moraine is broader, and the wells are not so deep, but show thicknesses of drift varying from thirty to seventy-five feet.

The moraine bends to the northwest from MeMillan, and, owing to the dense forest covering this part of the moraine, can not be well outlined. Between McMillan and Unity there is appreciably higher land on the east side of the Little Eau Pleine River, where the drift in places is known to be at least ninety feet thick,

At Unity there is an appreciable thickening of the drift, as shown by both the topography and well records. North of Unity to the vicinity of Medford the moraine is not so well defined topographically, but there is somewhat higher land along the line of the moraine, as located upon the map, the drift along this line being much thicker than in the area to the east. From Unity to the Black River at Little Black, the moraine is believed to form the divide between the streams flowing to the Wisconsin River on the east and those flowing to the Black on the west.

In the vicinity of Colby and Abbotsford the moraine is overridden by the Third drift whose relatively thin deposits have tended to obliterate the surface features of the older moraine. The erosion by the head streams of the Little and Big Eau Pleine rivers in this locality, and some distance farther south, also tended to reduce the prominent feature of the old moraine. By a combination, therefore, of stream erosion and later glaciation, the moraine is indistinct in northeastern Clark County and along the border of Marathon County farther southeast.

The area of the Second drift within the curve of the Marshfield moraine, as should be expected, is characterized by a much greater abundance of drift, than that immediately outside of it in the region of the First drift. The topography of the area within this loop has none of the characteristic features of recent glacial deposits, but has the features of complete drainage wrought into a thick mantle of drift by streams eroding for a considerable period. The streams flowing through this area, like those cutting across the Marshfield terminal moraine, have in general penetrated to the underlying pre-Cambrian crystalline rocks or to the Potsdam sandstone. Numerous rapids occur in the Black River and its tributaries, but none are known of boulder origin.

The known thickness of the terminal moraine varies from 30 to 170 feet. The average thickness of the moraine in its thickest portion, that is, the broad summit of the ridge, from one-half to one mile wide, is probably between fifty and seventy-five feet. This thickness will at least

The drift back of the moraine varies from a few feet up to 100 feet. No wells are noted within this area showing a greater depth of drift than 100 feet. Many well records show a thickness of twenty to seventy feet of drift. It should be remembered, however, that most of the farm houses are built upon the gently sloping upland where the drift is appreciably thicker than along the stream bottoms. If the drift of this formation, including also the drift of the first formation underlying it were spread out with uniform thickness over this area it would form a mantle probably between twenty and thirty feet thick. The Second drift, which forms the surface is ten times as thick as the First drift which underlies it.

The depositing of this thick drift has entirely changed the contour of the surface as it existed before the drift was laid down. It has not only filled up valleys but has also buried many hills and ridgy divides. The entire area of this drift formation is underlain here and there with the Potsdam sandstone. In the southwestern part of the area where the deeply overlaid sandstone hills and ridges are of the same nature as those to be seen on the surface still further southwest, the land is naturally more rolling than in the northwestern part of the county where the drift lies in the region of the gently sloping pre-Cambrian peneplain.

The Third drift overlies the northern part of Clark County, its southern border or moraine, generally speaking, crossing Colby, Green Grove, Longwood, Reseburg and Worden townships, This border, as a rule, produces no prominent feature of landscape being marked only here and there by drift ridges and morainic topography.

One mile west of Colby, in the southeast corner of Section 14, Town of Colby, is a gravel pit having the general character of the Third drift rather than that of the older First or Second formations. In Sections 16, 17 and 20 of Colby, are considerable ridge-like accumulations of drift whose surface features and character of drift indicate them to be Third drift. Similar drift hills occur a few miles farther west in the valley of the South Fork of Poplar River, in the southeast one-fourth of Section 22, Town of Green Grove, and also in the vicinity of Longwood.

In the vicinity of Colby the Third drift overrides the Second drift, but in this locality the Second moraine is apparently greatly eroded and is barely distinguishable. In the area north of these drift ridges there are occasionally shallow sags and undrained areas indicating comparatively young topography, while to the south the land surface is characterized by relatively sharp valleys and complete drainage everywhere. The drift of these ridges and that of the surface to the north is quite fresh and not much weathered, while that to the south is characterized by the yellowish brown color and advanced decomposition of the older drift formations.

West of the Black River the border is marked by a belt of shallow sags and low hummocky drift ridges extending through the central parts of the towns of Reseburg and Worden.

A characteristic of this region back of the border consists of its knobs and ridges, generally consisting of a few good sized boulders on top with much gravel and sand underneath the surface, the gravel greatly predominating. Locally these ridges are sometimes called gravel knolls or gravel ridges. There deposits represent recessional moraines, that is, the lines where the edge of retreating ice lingered for awhile, as contrasted with the terminal moraines which represent the outer edge of the ice lobe at its highest stage. There appears to be a belt of recessional moraine extending along the border of Clark and Taylor counties.

In Sections 4, 9 and 16 of the town of Hixon, the drift is accumulated in ridges of considerable size, some of the ridges reaching heights of thirty or forty feet above their surroundings. The ridge near the south quarter post of Section 4, is cut across by the wagon road and coarse bouldery drift is exposed. This ridge trends slightly west of north. Near the center of Section 9 the Wisconsin Central Railroad has cut through ten or fifteen feet of drift, showing the characteristic fresh drift of the Third formation overlying five or ten feet of the very old yellow red till of the Second formation. The lower drift is very much weathered and consolidated and is quite different in these respects from the overlying fresh gray drift. East of the moraine ridges in this vicinity the land is flat without any observed terminal moraine features to the vicinity of Sections 2, 3 and 4, of the town of Hoard. These isolated patches of moraine deposits, however, may very well mark the border of one of the recessional stages of the Third ice.

The thickness of the Third drift formation along the border varies from a few feet up to fifty or sixty feet. Some of the drift hills along the border, and also those which mark the stand of ice at recessional moraines, have a height of ten or fifteen feet up to forty or fifty feet above their immediate surroundings. Outside of the area of the moraines the drift in this region probably does not exceed a thickness of ten or fifteen feet. In some places it is only a thin mantle of two or three feet and in some places is entirely absent. Although thin, the deposits of this Third drift, unequally laid down, has modified somewhat the rough contours of the earlier land surface, but is not deep enough to cover the rugged sandstone hills.

As already stated, in addition to the glacial drift sheets, a small portion of the surface formation of Clark County, possibly some twenty-five square miles, consists of alluvial deposits, that is, deposits laid down in times past by the rivers and streams. These deposits are composed of clay, sand, gravel, and occasionally large pebbles or boulders, The sand and gravel is a porous formation into which the rainfall sinks to the approximate level of the adjoining streams. The clay beds seem to have a variable thickness up to ten or twenty feet, both underlain and overlain by a variable thickness of stratified sand and gravel. The Black River has the source of many of its streams in the terminal moraine of the Wisconsin drift sheet, flows southwestward across each of the older drift formations, and across the stratified gravel and sand plain of the southwestern part of the area and beyond, to the Mississippi. Beginning at the south the stratified gravel and sand of the alluvial deposits extends up along the Black, spreading out for many miles on either side, as far as the vicinity six or seven miles below the well defined terminal moraine of the Second drift sheet, which lies across its valley at Neillsville. From its source to seven miles below Neillsville the river flows through formations of bouldery drift, sandstone and crystalline rock, its channel being in marked contrast with the terraced river deposits beginning seven miles south of Neillsville. Thus along the Black River, the valley deposits do not continue northward to the Wisconsin terminal moraine, nor even to the thick moraine of the Second drift.

The Eau Claire River in western Clark County has well defined alluvial deposits far up its course from the Chippewa River, but these terminate within the area of the oldest drift of the district in western Clark County.

With respect to the distribution of the alluvial filling and the several drifts, it may be stated that the filled valleys extend indiscriminately across the area of the First drift sheet.

A feature of the landscape in the southwestern part of Clark County consists of the castellated hills which rise through the morainic deposits as nunataks. These are hills which were once completely surrounded by the ice, though never overridden. They are limited to the border of the glaciated region where the ice was thin.

The castellated bluff or mesa of iron-stained sandstone at Humbird is one of the most accessible of these nunataks. The Chicago & North Western Railway passes close by its base. The ice of the continental glacier wrapped completely around the foot of this nunatak. The ice sheet terminated less than a mile to the southwest. Hence it was so thin at this point that it never rose to any considerable height on the slopes of the mesa. This is demonstrated also by the castellated and craggy character of the nunatak,

The Neillsville nunatak in Clark County is of the same character as the one at Humbird. Both are exactly like the mesas and buttes of the Driftless Area, except that they are surrounded by glacial debris. At Neillsville a long narrow ridge is made up of a series of castellated sandstone crags and towers. On the lower slopes are glacial boulders, but none are found on top.

The question has been raised as to whether the Neillsville ridge might not have been glaciated and subsequently restored to its pre-glacial form by weathering. It seems certain that there has been far too little time for this. A period long enough for such profound weathering would be more than ample time for the destruction of all the glacial drift in the surrounding region, or its burial beneath a thick covering of sandstone talus. As a matter of fact the sandstone detritus nearby is very slight in amount and the erratics are exceedingly well preserved even for older drift. On the northern slope of the mound is a marked terminal moraine. No hesitancy is felt in asserting that the Neillsville ridge is a true nunatak,

This nunatak furnishes a rough measure of the slope of the continental glacial in Central Wisconsin. This castellated ridge is about ten miles from the outermost stand of ice. Its crest is between 1,400 and 1,500 feet above sea level. No erratics are found within 200 feet of the top. The elevation of the terminal moraine to the southwest is between 900 and 1,000 feet. If we assume that the ice rose steeply to a height of 50 or 100 feet at the border of the Driftless Area and then sloped gradually northeastward to the Neillsville nunatak, its surface gradient was not more than fifteen or twenty feet to the mile.

1 - This chapter is condensed from: Samuel Weidman, The Geology of North Central Wisconsin (Madison, Wis., 1907). The article on the nunataks is from: Lawrence Martin, The Physical Geography of Wisconsin (Madison, Wis., 1916). These works, published by the state, and illustrated with copious maps and plates, should be studied by all who are interested in the study of the Physical Features of Clark County. The reader is also referred to the Reconnoissance Soil Survey of the South Part of North-Central Wisconsin, prepared by investigators representing the United States Department of Agriculture in co-operation with the Wisconsin Geological and Natural History Survey, and published by the Government Printing Office at Washington, in 1917.