Prairie potholes are wetland depressions --- primarily freshwater marshes --- found in the Upper Midwest from the Dakotas to Wisconsin. This formerly glaciated landscape is pockmarked with many potholes that fill with melting snow and rain in the spring. The smaller “holes” with few surrounding hills are temporary springtime wetlands that quickly evaporate during the warm summer months; many of these smaller depressions have been deliberately eliminated or are annually drained by farmers. Others, however, like Rose Lake are essentially permanent due to the rain water running off and percolating from the surrounding hills, especially on the west side where you are standing. Furthermore, a few springs bubbling up at the south end of the marsh supply some water into the drier autumn months. But in the course of the growing season, the water level will dramatically fluctuate, and the area will drastically change its appearance as the amount of open water shrinks, and the plant life characteristic of marshes emerges and dominates the wetland. In 2003, for example, when rainfall was below average, the “lake” nearly dried up; while in 2008 and 2009 the water levels were memorably high due to excessive precipitation.
Standing at the observation deck, you soon realize that Rose Lake like other shallow lakes and marshes in Wisconsin is alive with birds, especially migratory waterfowl that reside in the marshes as well as the surrounding savannas and prairie grasslands.
To receive geo-credit, please email --- do not publicly post --- your responses to these four questions. Use the information at the observation deck as well as your own eyewitness observations to answer the questions.
1. The elevation of Rose Lake is 844 feet. What is the elevation at the observation deck?
2. In an average year, what is the greatest depth of this prairie pothole called Rose Lake?
3. Looking closely at the “lake” and not the surrounding woods, you see that Rose Lake consists of three distinct features: (a) open water, (b) wetlands, and (c) ___________ [supply the missing feature].
4. The fact that freshwater sponges are found here indicates that the waters of Rose Lake are relatively _____________ [one-word answer].
Sources:
http://water.epa.gov/type/wetlands/potholes.cfm to access Duck’s Unlimited’s Teacher’s Guide to Wetland Activities
www.jeffersoncountywi.gov/plans/Dorothy_Carnes_County_Park_Master_ Plan_2009.pdf to access Dorothy Carnes County Park& Rose Lake State Natural Area Master Plan: October 2009 Prepared for: Jefferson County Parks Committee.
http://en.wikipedia.org/wiki/Prairie_Pothole_Region to access Wikipedia’s – Prairie Pothole Region.
Permission to post this earthcache in Dorothy Carnes County Park was given by: Joe Nehmer, Jefferson County Park Director, and Thomas A. Meyer, Conservation Biologist, Wisconsin Dept of Natural Resources.