To claim this as a find you will need to complete the three tasks outlined below. Failure to complete the tasks may result in the deletion of your log without notice. Be sure to Bring Your Camera – you may want to keep it out and visible while at the park*.
You are on top of a hill overlooking Lake Monona, with the Yahara River running through the lake. 50,000 years ago, if you were here overlooking the Yahara River, the view would have been much different.
You would have been standing at the top of a deep, narrow, river valley, with the Yahara River flowing far below you. Before the last glacier the Yahara River flowed at the bottom of a steep valley, with the valley walls soaring as much as 600 feet above the river. After cutting through resistant Black River limestone, the weak St Peter sandstone beneath would create short, steep slopes on the valley wall. Next was a resistant layer of Lower Magnesian limestone followed at the bottom of the river valley by weak Cambrian sandstone. The surrounding area was also characterized by tall, steep hillsides running down to streams and rivers.
The last advancement of Pleistocene glaciation, the “Wisconsin Stage” generated a massive tongue of ice known as the Green Bay Lobe which flowed from the northeast to the southwest. The Green Bay Lobe flowed over the Madison area, grinding down hilltops and filling up valleys with glacial deposits. As the Late Pleistocene global climate began to moderate, the ice edge fluctuated back and forth across the area for several thousand years, dumping and reworking quantities of glacial debris sufficient to nearly fill the ancient river valley. Because the Yahara River was in the weak Cambrian sandstone, the glacier was able to scoop out the sandstone and greatly deepen and broaden the river valley, creating the lake basin.
When the glacier finally retreated from the area, between 10,000 and 12,000 years ago, it left behind a chain of lakes - Mendota, Monona, Waubesa, and Kegonsa where the steep, deep, Yahara River valley used to be.
To claim this find you must complete the three tasks below:
1. Estimate the change in the visible relief due to the glacier using the following steps and email your estimates to me when posting your "found it" log
Across the lake to your left is the Monona Terrace, a rounded building with large windows right on the lakefront:
a) Estimate the height of the Monona Terrace
b) Imagine how the area looked before the glacier arrived. How many Monona Terraces would you have to stack one on top of the other to reach from the bottom of the river valley to the top of the valley walls?
c) How many Monona Terraces would you have to stack one on top of the other to reach from the lake surface to the top of the hill you’re standing on now?
d) What’s the difference in the number of Monona Terraces?
2. Do you think the glacier had a major impact in the topology of the area? Why or why not?
3. BRING YOUR CAMERA. Although no longer required, we would appreciate a photo of you/your team with your GPSr at Olin Park, with the lake and Monona Terrace in the background. If you are solo caching, a photo of your GPSr with the lake and Monona Terrace in the background will also be appreciated. Please upload your photo(s) with your "found it" log.
1. The Physical Geography of Wisconsin by Lawrence Martin
2. Lakeshore Nature Preserve - www.lakeshorepreserve.wisc.edu