Geology of the Ice Age National Scenic Trail

Middle Kettle Moraine Ice Age Trail Segments

T he Middle Kettle Moraine, as used in this book, extends from the Fond du Lac—Washington County line southward to Interstate 94 (I-94) near Delafield (fig. 104). Unlike the northern and southern parts of the Kettle Moraine, much of the land here is under private ownership. Nonetheless, there are 13 trail segments that exhibit glacial features typical of the Kettle Moraine: eskers (SB 13), moulin kames (SB 12), and kettles (SB 9) dominate the landscape. In places, pitted outwash (SB 10) is extensive, and in the southern part of this area there are a number of large meltwater channels . As in the Kettle Moraine north and south of here, nearly all of the sediment is sand or a combination of sand and gravel that was deposited by meltwater. There are few examples of till exposed anywhere in this part of the Kettle Moraine. Thus, the Kettle Moraine is not a moraine by most definitions but instead is an interlobate zone where supraglacial and subglacial streams deposited sand and gravel. Much of the northern Kettle Moraine consists of two distinct ridges separated by a low area of outwash or till. The middle Kettle Moraine is more complex. In places there are two clearly defined ridges separated by a low area, but throughout most of this section, the ridges merge into a single broad mass of sand and gravel. North of the Slinger or Cedar Lakes Segment (fig. 104), meltwater from the retreating Lake Michigan Lobe drained away from the Kettle Moraine and toward Lake Michigan. From there southward the Lake Michigan Lobe meltwater flowed into and sometimes across the Kettle Moraine, leaving behind broad channels that are now occupied only by small streams. Mickelson and Syverson (1997) interpreted the formation of the single-ridge Kettle Moraine in Washington County to be similar to that shown in figure 105. 131 Middle Kettle Moraine Ice Age Trail Segments Figure 104. Shaded relief of the middle Kettle Moraine IAT segments (red): (17) Milwaukee River Segment in Washington County, (18) Kewaskum, (19) Southern Kewaskum, (20) West Bend, (22) Cedar Lakes, (23) Slinger, (24) Pike Lake, (25) Holy Hill, (26) Loew Lake, (27) Monches, (28) Merton, (29) Hartland, (30) Delafield. Blue arrows show ice-flow direction. Yellow lines and numbers indicate highways. Cities shown (yellow): (H) Hartland, (Ha) Hartford, (K) Kewaskum, (O) Oconomowoc, (P) Pewaukee, (T) Theresa, (W) West Bend. GBLD: Green Bay Lobe drumlins; LMLD: Lake Michigan Lobe drumlins. (Base map constructed from USGS National Elevation Dataset and modified by WGNHS.) Figure 105. History of single-ridge Kettle Moraine formation in Washington County. (A) Advancing Green Bay and Lake Michigan lobes meet in the interlobate region. The upward flow of ice brings debris from base of ice to surface. Subglacial streams flowing in tunnels deposit sand and gravel. (B) The ice thins. Meltwater streams at surface transport and deposit sand and gravel in interlobate corridor. More subglacial tunnels form in interlobate region. Meltwater finds its way to base of ice through moulins. (C) Glacier lobes separate from the interlobate region. Thick debris insulates underlying ice. Hummocky topography develops as underlying ice slowly melts. (D) Hummocky sand and gravel lowers as underlying ice continues to melt, forming most high areas in Kettle Moraine. Eskers remain as prominent ridges in the Kettle Moraine. (Modified from Mickelson and Syverson 1997; drafted by Mary Diman.) 17. Milwaukee River Segment in Washington County Kettle Moraine Dr. to CTH H (4.7 miles) This segment of the IAT follows the high-relief hummocky topography (SB 11) of the Lake Michigan Lobe side of the Kettle Moraine. You will find deep kettles throughout (fig. 106). There are some good views through the trees of individual moulin kames (SB 12) in the low, central part of the Kettle Moraine to the west. The low flat areas are outwash (SB 8), but in places they have thin peat on the surface. About 1 mile west of where the trail crosses STH 28, a small esker (SB 13), partly mined away, crosses the highway. You’ll find a cluster of small moulin kames (unlabeled) just west of the trail (north of STH 28) and a very large kame (unlabeled) south of the highway. The trail continues on the Lake Michigan Lobe side of the Kettle Moraine to CTH H across high-relief hummocky topography. 18. Kewaskum Segment Eisenbahn State Trail to Ridge Rd. (2.2...