How does that song go?
"One of these things is not like the others,
One of these things just doesn't belong,
Can you tell which thing is not like the others
By the time I finish my song?"
As this is part of the Waukesha County Park System, they have asked me to inform visitors that they are to park in the car only area and pay (at the self-registration box) $5.50 for a week-day visit and $5.75 for a week-end visit to this boat launch. Fulfilling your tasks at this location should take approximately 5 minutes and involves simple visual observations.
Permit #2011-29
Oconomowoc-Waukesha Lake District
There are about 45 water bodies in the Oconomowoc-Waukesha Lake District. This series of lakes has a northeast-southwest trend and extends from Lake Five to the northeast and Golden Lake to the southwest. In general this district lies in a break in the kettle moraine. Most all lakes in the district were formed by chunks of ice left behind and covered in glacial drift as glaciers passed through the area. Many of these water bodies are “kettle lakes” and are filled with water year-round. Other kettles in the area are above ground water level and rarely fill with water or do so only during flood level events. The process of kettle formation can be seen below:
Kettle Lake Cavity Formation
Many lakes in the area were formed by melting blocks of ice at the end of the last Wisconsin Ice Age approximately 13,000 years ago. As glaciers advanced and retreated, some of the ice blocks were trapped in one spot or were more difficult to melt than other ice flows in the same area. As the free moving glaciers continued to flow they deposited sediments (also known as outwash or glacial drift) around and sometimes on top of these isolated ice blocks. As the ice blocks melted, they left behind depressions in the ground. Many of these depressions filled with snow melt and rainwater producing kettle lakes. Most kettle lakes are less than 1.25 miles in diameter. By comparison Pewaukee lake is over 4 miles long.
Pewaukee Lake Formation
Pewaukee Lake’s formation is different. Chancey Juday wrote in The inland lakes of Wisconsin, Issue 27, “Pewaukee lake differs in origin from the other lakes of this district. It is situated in an area of ground moraine and the basin it occupies resulted from the failure of the glacier, which moved westward down an ancient river valley, to fill this portion of the valley with morainic material; in fact, the basin may even have been deepened by the glacier.” So you see that Waukesha county's largest lake is unique to the area.
Glacial Drift / Outwash
The thickness of glacial drift near Pewaukee Lake is unusually shallow for the area and the limestone which typically lies beneath the ground can be seen at the surface in a few places. One of these exposures is at Rocky Point (directly east of ground zero) where limestone can be seen at the water’s edge. Because of the ease at which the limestone could be found here, in 1844 a quarry was built to mine it and other stone. As you go further from the lake glacial drift has been found to be 100 (or more) feet deep.
LOGGING THIS EARTHCACHE
In order to log this EarthCache you must email me the answers to the following questions:
a. You are on the west end of the lake. Looking straight out across the lake, where do you think the lake valley walls are: straight ahead (east) to the right (south) or to the left (north)?
b. Going to the waterline and looking right (southwest): what type of terrain is there? Is there an exposure of limestone?
c. Reading the cache page and using some critical thinking: there is an island in front of you to the east…what do you think forms its base?
d. Again reading the cache page and using some critical thinking: Assume you come to another lake just outside this district, it's half the size of Pewaukee Lake. How likely is it that that lake is a kettle lake?
References:
- The inland lakes of Wisconsin, Issue 27 CHAPTER IV. THE OCONOMOWOC-WAUKESHA LAKE DISTRICT By Chancey Juday
- http://www.visitwaukesha.org/history.html
- http://bongo-www.thefullwiki.org/Kettle_lake
- One of These Things (Is Not Like The Others) Words and Music by Joe Raposo and Jon Stone