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A continental divide is a topographic feature – a natural boundary line of elevated terrain which forms a border between two distinct watersheds. This border means that streams, rivers and waterways along the divide are separated with water flowing toward opposite sides of the continent. Continental Divides result over millions of years during the formation of the earth as mountain ranges form and the earth’s crust folds, terrain erodes and ridges and peaks that are now defined as divides are formed.
In North American there are five continental divides: Eastern, Northern, Great, Canada and this St. Lawrence River Divide. The St. Lawrence River Divide separates the Atlantic Ocean water shed and the Great Lakes Basin.
At the coordinates of this earthcache, you will find the sub-continental Divide as it runs through Wisconsin at Hwy 33 in Washington County.
This sub-continental divide intersects the seven county region as shown in the map above. While the population growth of the region has had a great effect on the ground water flow system, the geology or hydrogeology (ground water flow) has remained ever so constant.
For the purpose of this earthcache, I wanted to explore this constant so you can gain an understanding of the aquifers of our area that this sub-continental divide helps feed.
Our region has three principal groups of rocks, each containing aquifers:
- 1. Shallow unlithified material containing sand and gravel aquifers (Shallow part of flow system)
- 2. Shallow bedrock containing the fractured dolomite aquifer (Shallow part of flow system)
- 3. Deep part of the flow system containing the sandstone aquifer
Along Lake Michigan, the shallow and deep parts of the flow system are separated by the Maquoketa shale, an aquitard that keeps the deep sandstone under pressure.
Most municipal pumping in cities near Lake Michigan is from deep bedrock.
There is plenty of room for safe parking off the roadway. At this point, you will be able to observe the natural boundary line forming this ridge.
Enjoy your visit!
To log this earthcache, you must complete TWO tasks.
1) Email me the answers to the following questions:
- A. According to the definition of a divide, the actual ridge should be at a higher elevation that the surrounding land. When you are facing the historical marker, is this ridge to your right or to your left?
- B. How many feet above sea level AND how many feet above Lake Michigan is this ridge?
- C. Water on the west side of this ridge travels down what river and eventually this reaches what major body of water?
- D. Water on the east side of this ridge travels down what river and eventually this reaches what major body of water?
If you like, bring a container of water. Pour it onto the grass or asphalt near the posted coordinates to see which direction the water flows.
2) BRING YOUR CAMERA. We would like a photo of your team with your GPSr so it shows you were here but please do not include the parts of the sign that give the necessary answers!
AuntieNae at the Divide
Gr8 Eyes at the Divide
Please be advised, failure to complete the TWO tasks listed above (emailing the answer and posting your photo) will result in log deletion without notice. PLEASE DO NOT POST A PHOTO OF THE SIGN UNLESS THE ANSWERS ARE WELL COVERED. THANKS
You do NOT have to wait for confirmation from me before logging your find. Please do not make any reference to the answers in your log.
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Special thanks to Team HoneyBunnies who adopted Little Otters traditional cache also at this location, for their permission for placement of this Earthcache.