|Home < Wisconsin < Geography < Western Upland|
The Western Upland of Wisconsin
The Western UplandThe landscape in western Wisconsin makes this one of the most attractive parts of the state. Owen, the first geologist to do detailed work in Wisconsin, said in 1847:
"The constant theme of remark, whilst travelling in the regions of the upper Mississippi occupied by the lower magnesian limestone, was the picturesque character of the landscape, and especially the striking similarity which the rock exposure presents to that of ruined structures."
Most of the region is a thoroughly- dissected upland, not a flat- topped or sloping surface as in northern Wisconsin or the region near Lake Michigan. The average elevation of the hilltops above sea level is about 1100 feet in St Croix and Pierce counties in northwestern Wisconsin, 1280 feet in Vernon County, and 900 to 1200 feet in Grant County. The uplands thus stand 100 to 200 feet above the Eastern Ridges and Lowlands to the southeast, and 200 to 350 feet above the Central Plain to the northeast.
Aside from the upland itself the strongest topographic features of the region are the great trenches or gorges of the Mississippi and Wisconsin rivers and their numerous branches. The gorge of the Mississippi is incised more than 500 feet below the level of the upland ridges.
The Two Cuestas
The upland or plateau region of western Wisconsin consists of two cuestas and one monadnock. A cuesta is an upland belt with a short, steep descent, or escarpment, on one side and a long, gentle slope on the other. Most of the province is not a flat-topped upland or plateau, but a thoroughly dissected cuesta. With the except of the area northwest of the Chippewa River, it has no smooth upland areas of notable extent. It is a region of high, narrow ridges and deep, steep-sided valleys.
The northern four-fifths of the Western Upland lies in the belt of Lower Magnesian limestone, and to a smaller extent in the area of the Cambrian sandstone. The southern fifth of the province lies in the belt of Galena- Black River limestone. A small portion of the Western Upland is the Baraboo Range. This is not a cuesta, but an exhumed monadnock made up of pre-Cambrian metamorphic and igneous rocks.
Ridges and Coulees
Between the Chippewa and La Crosse rivers is a farily broad and not very hilly upland, while the higher region between the Chippewa and the La Crosse has been dissected into a system of ridges and valleys, with practically no upland area remaining. The hilltops do not exceed 1100 to 1300 feet above sea level.
The French name coulee is the designation for valley which is prevalent in [this region, which] occupies all of Buffalo and Trempealeau counties and parts of La Crosse, Monroe, Jackson, Eau Claire and Pepin counties.
Fossil Stream Courses Within the Cuesta
Ancient stream gravels at Seneca in Crawford county, Windrow Bluff in Monroe County, the Baraboo Bluffs, and upwards of a dozen other places in adjacent parts of Wisconsin . . . preserve evidence of former river courses. The gravels appear to have been laid down 50 to 60 million years ago in creek bottoms and river flats. One of these streams lay parallel to and west of the present Kickapoo River.
The Baraboo Range
The Baraboo Range extends east and west in Sauk and Columbia counties, having a length of 25 miles and an average width of from five to 10 miles. It contains the Devils Lake State Park. The range is a monadnock, similar to those in northern Wisconsin. It differs from them in having been completely buried and now being only partially exhumed. As a matter of fact, only the eastern half of this monadnock stands very high above the adjacent country. The western half of the Baraboo Range is still buried in the Western Upland.
The summit altitude of the Baraboo Range varies from 1140 to 1620 feet. The greater part of it is from 1200 to 1400 feet above sea level. The western portion of the range rises only one or two hundred feet above the upland of Lower Magnesian limestone, while the eastern half stands 400 to 800 feet above the plain of Cambrian sandstone.
The Military Ridge
A well known topographic feature in southwestern Wisconsin and eastern Iowa is popularly known as the Military Ridge. In Wisconsin it constitutes the divide between the north- flowing tributaries of the Wisconsin River and the south- flowing streams tributary to the Rock and Mississippi. Its crest was followed by the Military Road, built in 1835 from Green Bay to Prairie du Chien, by way of Fond du Lac, Portage and Blue Mounds. Doubtless the existence of the Military Road was responsible for the location of the territorial road between Milwaukee and the lead and zinc district soon after 1837. It came by way of Madison and joined the Miltary Road southeast of Mt Horeb.
Herbert Quick [described] the heyday of its use as a highway of immigration from Milwaukee and Madison to Dubuque, Iowa over the back slope of the cuesta:
"It was in the latter part of March. There were snow- drifts in places along the road, and when I reached a place about where Mt Horeb now is, I had to stop and lie up for three days for a snowstorm. I was ahead of the stream of immigrants that poured over that road in the spring of 1855 in a steady tide . . .
Military Ridge is a name applied to a divide on a cuesta. The name is very convenient, for the ridge separates the two parts of the cuesta . . . : (a) the narrow, north- facing escarpment, and (b) the broad, south- sloping upland.
Blue Mounds and Other Niagara Outliers
The Blue Mounds outliers of the Niagara escarpment are 45 to 55 miles northeast of the nearest portions of the Niagara cuesta in Illinois and Iowa, and 69 miles west of the Niagara cuesta of eastern Wisconsin. They may be regarded as having been left behind by the recession of either the escarpment to the east or that to the southwest. Between Blue Mounds and the front of the cuesta near Dubuque are (a) Platte Mounds and (b) Sinsinawa Mound, 25 and 10 miles respectively from the escarpment in Iowa, and (c) the mound near White Oak in Lafayette County, five miles from the escarpment in Illinois.
Valleys in Southwestern Wisconsin
The valleys in the upland of southwestern Wisconsin are cut rather deeply into the upland. The grades are steeper than the slope of the upland, so that the valleys increase in depth to the southward. Near their mouths, the main valley bottoms are 200 to 300 feet below the ridge tops.
Many of the valleys and slopes of southwestern Wisconsin have been gullied notably in recent years. [It is probable] that gullying has been induced by man's activities in cutting down forests, ploughing fields, excavating mines or otherwise disturbing nature's balance in the surface drainage or the underground circulation.
The Driftless Area is mostly in the Western Upland, but it also extends into the Central Plain and the Northern Highland. It covers an area of nearly 15,000 square miles, 13,360 square miles of which lie in Wisconsin with the remainder extending into Minnesota, Iowa and Illinois.
Writing in 1854, Edward Daniels, the first state geologist, described the Driftless Area as follows:
"About one- third of the surface is prairie, dotted and belted with beautiful groves and oak openings. The scenery combines with every element of beauty and grandeur, giving us the sunlit prairie, with its soft swell, waving grass and thousand flowers; the somber depths of primeval forest; and castellated cliffs, rising hundreds of feet, with beetling crags which a Titan might have piled for his fortress."
The Driftless Area is driftless because of three factors:
In advancing over Wisconsin, the ice sheet or continental glacier was divided into several lobes determined in position by the preglacial configuration of the land. These were the Lake Michigan and Green Bay lobes on the east and the Lake Superior and Minnesota lobes on the west. On the north two minor branches of the Lake Superior lobe united to form the Chippewa lobe. The movement of these ice lobes is known by the glacial scratches upon the rock ledges and by the transported rocks or erratics which have been traced to their sources in Michigan, Minnesota and Canada. These lobes advanced until they completely coalesced.
The latest stage of glacial advance is called the Wisconsin stage of glaciation (whether found in Wisconsin or elsewhere). The deposits of earlier glaciation are spoken of collectively as older drift.
[The book includes an extensive discussion of the topography and physiography of the Driftless Area on pages 81-102, and contains an entire chapter devoted to The Discovery and Explanation of the Driftless Area beginning on page 103. Following this is a chapter on The Glacial Period in the Western Upland with references to, among other localities, the Baraboo Range and Devils Lake. There is a short section on Relative Value of driftless and Glaciated Land for agricultural purposes.]
"The Mississippi takes its rise in various lakes in the country of the Northern Nations. It is narrow at the place where Miskous (the Wisconsin River) empties; its current, which flows southward, is slow and gentle. To the right is a large chain of very high mountains, and to the left are beautiful lands; in various places the stream is divided by islands."
The gorge of the Mississippi furnishes the most rugged topography and picturesque scenery to be found in Wisconsin. This gorge has a length of more than 200 miles in Wisconsin, extending from Prescott (at the mouth of the St Croix River) to southwestern Grant County. In the gorge are bottomlands 1 to 6-1/2 miles wide, bordered by steep bluffs 230 to 650 feet high.
The gorge walls along the Mississippi are youthful, but the bottomland and the river itself have a more mature aspect. The floor of the gorge shows two conspicuous features: the floodplain of the river which occupies most of the bottomland, and the terraces which are narrow and discontinuous. The terraces (sometimes spoken of as second bottoms) furnish the sites of all the important cities and villages along the Mississippi.
The Mississippi terraces were made by glacial streams which originally deposited sand and gravel. Subsequently they cut away the large part of these depositions, leaving the terraces.
The original gorge of the Mississippi has been buried to a depth of 100 to 200 feet. The rock floor of the Mississippi slopes southward at a grade of six inches to the mile. The present grade of the river is a little less than four inches to the mile.
There are four episodes in the known history of the Mississippi:
Each of the Mississippi tributaries in the Western Upland, even those lying wholly in the Driftless Area, has had essentially the same episodes in its history.
[The book's next chapter discusses The Rivers Within the Western Upland, including the lower Wisconsin, Baraboo, Kickapoo, La Crosse, Black, Buffalo, Chippewa and St Croix rivers.]
Search for anything at Wisconsin Online!|