Some Exploded Theories…of Devil’s Lake

        By City Engineer H. E. French  

Read Before the Sauk County Historical Society,

February 17, 1908


The dotted line shows a cross section represented by the diagram below the map of the lake. The two straight lines represent the depth of the lake, while the curved line shows the quartzite bottom. The saucer shaped space is filled with dirt and rocks brought by the glaciers. It will be noted that the depth of the water, represented by the two parallel lines, in comparison with what has been filled into the old valley, is very small.  

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In leading up to the present physical facts and topography of Devils Lake , it rather becomes necessary to dwell upon the geological history of the lake and surrounding territory. In studying the history of the physical changes from the writings of the most eminent geologists, the first thing that impresses you in the denuding of the romantic theories and extravagant statements regarding the depth of the lake and the volcanic origin of its bluffs. From our ignorance of the first principles of geology we are naturally inclined to associate the wild, picturesque sheet of clear water with an air of mystery and romance, but instead of Vesuvius, bristling with its volcanic antics in ancients times, we have a passive, peaceful lake basin, formed by the most prosaic of agencies in the most simple and natural form of development, covering millions of years. I remember very vividly my first impression of the lake as being a confused mass of rocks tumbled in its present state in an instant from volcanic origin, the bluffs on all sides meeting at a point of inconceivable depths below the surface. It seems somewhat rude at first to discourage the local ideas, but if one will only take the time to read upon the subject, they will very soon be impressed with the fact, that there is just as much romance in the more natural geological development as in the picturesque ideas.  

Origin of the Lake  

Devils Lake comprises a very small portion of what the geologists call the Baraboo Range . This range is inclosed by the North, East, South and West Bluffs, covering a distance of 18 miles east and west and having a width varying from two miles at the East Bluff to 10 and 12 at the West Bluff and occupying about 225 square miles.  

The first stage or period of the lake’s development deals with the formation of the quartzite rock, which is nothing more or less than altered sand stone, but with the voids filled with silica or quartz, deposited by percolating water from the presence of the sea. This formation took millions of years and apparently destroys the volcanic theory on account of the absence of any igneous rock. The supposed

thickness of the quartz rock is 4000 to 5000 feet. Then came the withdrawal of the sea and the erosion of the gorge by streams and rivers. The Gorges at Ableman and Lower Narrows were probably formed at the same time. Thus the old original gorge was formed to an unknown depth taking ages and ages.

The second period dwells again with the presence of the sea, which beat against the island of quartzite forming the sandstone and limestone beds. This continued till the quartzite was entirely buried with the sandstone and limestone. Mr. Thwaites says remnants of limestone can be found on the East Bluff in an old well. This is call the Paleozoic Period covering ages.  

The third period deals again with the withdrawal of the sea and the re-excavation of the gorge by the Wisconsin and the Baraboo rivers. The Wisconsin river is supposed to have come through the Lower Narrows joining the Baraboo river and flowed out through the Devils Lake gorge, meeting the present course at Merrimack . This erosion continued till the gorge was 800 feet lower than the present bottom. There is a question whether the Wisconsin continued to flow with the Baraboo river through the gorge or whether it was diverted to its present course, but it is certain that the Baraboo river continued to flow out through the gorge.  

No Volcanic Action  

We can readily see how the tumbled mass of quartzite rock was taking its final position. As the heavy beds of quartzite took new positions due to the erosion, the rocks slipped or sheared along the lines of least adhesion or cohesion. The whole quartzite pile is made up of a system of vertical cracks, so to speak, dividing the whole into a series of vertical blocks of columns which originally were all in contact with each other. The isolated columns and pillars, as the Devil’s Doorway and Turks’ head, etc., have been left as they now stand by the falling away of the blocks which once surrounded them., This can not  help but appeal to one’s reason in comparison to being thrown up there by volcanic action and happening to balance themselves accidentally as you now see them.  

The fourth period brings us to the presence of the glacier. The so called Wisconsin glacier at this point advanced farther west than any of the five earlier ice sheets. It was split by the high east bluff and advanced many miles father down the Wisconsin and Baraboo river valleys, than it did on the bluffs. This caused its edge to cross the Devils Lake valley in two places, evidences of which can be found in the terminal moraines at the north end of the lake and across the deep cut of the C. & N. W. east of the lake. These moraines of sand, gravel and boulders, left on the retreat of the glacier, formed the little basin you now see and diverted the Baraboo river to its present course.  

Size of the Lake  

 The following is information gained by the hydro-graphic survey made by Mr. F. T. Thwaites, G. K . McConnel and Madison, H. E. Cole and myself on January 20th. Five different cross sections were run across the lake and about 80 soundings taken at intervals varying from 100 to 300 feet.

  Greatest length –6,700 feet or 1 ¼ miles.

  Average width—2,200 feet of 2.5 miles

  Greatest depth—43 feet

  Average depth—30 feet

  Circumference—3 ¼ miles

  Area—388 acres or 3.5 sq. miles.

  Volume at low water—17,258,000 cubic yards (3,495,245,000 gals.)

  Above sea level—low water, about 955 ft; high, about 959 ft.

  Area draining into lake—about 5 ½ sq. miles

  To anyone who might be skeptical on the subject, I would advise that they take the time to read “ Salisbury and Atwood’s Devils Lake and Dalles.” I am also indebted to Mr. Thwaites of Madison for certain statements in this article.