Walworth County, Wisconsin - Chapter 1: Pre-Glacial Epoch - Geological Formations, 1912

A few of the more plainly told facts or statements derivable from the state and federal geological surveys may at least provisionally account for the present face of Walworth county. In a prc-glacial age (its beginning and end not to be more nearly estimated in calendar years than arc Mar distances in statute miles) the rock floor of the southern tiers of Wisconsin counties was of latest formation and uplifting from the dark waste of waters. As to that backward-stretching segment of eternity, geology is at one with Genesis: "The earth was without form and void; and darkness was upon the face of the deep." At the beginning of the period called "eocene" - morning of life - and by American writers also named Laurentian, an almost solitary island of granite or crystalline rock's, in outline a mdely made V, covered most of Labrador, a large part of Quebec and Ontario, and the more northerly province of Kewatin. It had its lower point near the southern shore of Lake Superior, and it enclosed between its arms a larger I tudson's bay.

and in other ways distorted by upheaval, and. perhaps, b; ubnce, rose to far greater heights than arc now I 1 be seen on earth. II high they wen- is only inferred by widely varying but uncertain depth and breadth the later sedimentary and cal posits formed by nature's continent-making agencies, in great part, at least, from the disintegrated and recomposed materials of those overtowering ranges and peaks. The thickly-shrouding vapors which had long shut out the light of sun and stars were condensed to water that gathered itself into destructive torrents, and the acid-laden atmosphere waited like an obedient servant upon the spirit of the flood. There were other helps doubtless, but their dim and confused record is best translated or hypothetically explained by patientlyobserving and ingeniously-conjecturing geologists.

When the solid foundation was laid the surface of the county was left far from even. At several points within the county borders the upperlying rock has been found, by measurement of deep wells, at heights above sea level ranging say. between 480 and 870 feet - or from 100 feet below to nearly 300 feet above the level of Lake Michigan. Great variation of height has been found at points but a mile or less apart. The bottom of the low-lying pre-glacial Troy valley was found at 480 to 500 feet; in East Tro_\ and Spring Prairie at 530 to 820 feet; in Lyons and Bloomfield at 643 to 8 11 1 feel : in Troy and Lafayette at 480 to 840 feet: in Geneva and Linn at 700 to 870 feet : in LaGrange and Whitewater at (:>6^ to 850 feet; in Sugar Creek and Richmond at 600 to 830 feet: in Darien and Sharon at 780 to 810 feel : in Delavan and Walworth at 500 to 800 feet; at Elkhorn 810 feet. These measurements, though too few and perhaps too inexact for a sailing chart, may show that the following glacial movements and meltings left the surface of the county much better graded for its present uses. An ideal column of under lying strata, as shown by the state's geologist is. in order of til

For more than one-half of the county the Niagara stratum is wanting, and. as depicted on geological charts* a ribbon-like belt of Cincinnati shale (dipping toward Lake Michigan 1 divides it from the Trenton and Galena formation. The shale bell reaches from the Illinois line, by way of Linn

It is not to be known how many ice sheets have successivel} covered some part or all of the county's area, but the so-named Green Bay and Lake Michigan glaciers brought the lower loop of the great Kettle moraine into the northern part of Lagrange and Whitewater. An attendant or soon following offshoot of the latter-named glacier moved across Milwaukee. Waukesha, Racine and Kenosha counties and the lake-shore counties of Illinois, and formed the Valparaiso moraine, which reached from Waukesha county to Porter county, Indiana, having Burlington in its line of invasion. A spur or branch, now named the Delavan lobe of the Lake Michigan glacier, was pushed across Walworth, covering most of its southern half and its northwestern quarter, and meeting the Milton and Johnstown moraines of Rock county westward and the Marengo drift southward. Delavan lake and its outlet divides this lobe, and hence the Darien and Klkhorn moraines. I charts also show a conjectural Genoa moraine less plainly indicated, bul nol improbable.

The latest and most likely greatest of these invading and overwhelming ice sheets found here its southmost limit. The arrested mass, heavily weighted with the abundant and various spoils of its northern conquests, began the long period of its dissolution. As it slowly dropped its burden of clay, sand, gravel, pebbles, and boulders its rising torrents found or forced their outlets by the winding ways of the present creeks, the valleys of which are now far wider than needful to carry gulfward the little floods of spring and autumn. To the action of moving and melting glaciers is .ascribed the sent contour of the county. It may be supposed that the irregular surface of the latest rock deposits turned and in other ways affected the general course of the glacier across the county, and that fragments of the e ocl were borne along from the eastern side of the county to be dropped in and counties lying some miles westward. It is even imaginable that the tremendous force of the moving mass -tripped the western part of the county of it- Niagara stratum, for such effeel el ewhen are attributed to such cause. It is also possible that the Elkhorn moraine was formed later than the parallel Darien moraine, as the melting mass presented the aspect of a body retreating with its face to the front. x lorn about a quarter of the county is covered with the earlier moraines, the i terials far-brought from the north and mixed with a large portion of pebbles has been found of greatly varying depth ; as at Elkhorn about 275 feet ; at points of the Darien moraine from 400 to 600 feet; at Yerkes Observatory (in Walworth) 405 feet; at adjacent points in southeastern Rock county 40 to 100 feet.

It can not be said with strong assurance that nature's tremendous formative work is yet finished for this county. The earthquake vibration of [908, so distinctly perceived at Chicago, Aurora, and other points not farther away, were also felt for an instant here - barely felt, but unmistakably. It is probable that no place between the poles, whatever its latitude, is wholly and forever exempt from the action of cosmic or of subterranean forces, though man very reasonably believes that this earth, if not made expressly for his home, has been made generally habitable for him. The dwellers of Walworth do not as yet feel as insecure as if they had chosen their homes at the foot of the Andes.