Kettle Kampeska EarthCache
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In order to count this Earthcache as a find, you must complete the following tasks and email the answer to me.
1. Estimate the distance across the lake.
2. Describe the sediment that makes up the shoreline of the lake.
3. Describe the shape of the lake. How did it get its shape?
This Earthcache is located along the shores of Lake Kampeska at Memorial Park. Lake Kampeska is an example of a kettle lake--a lake produced by a retreating glacier. This lake access offers camping, playgrounds, a boat launch, a beach, and a swimming area. Enjoy!
The glacial history of South Dakota is usually established as beginning with the onset of the last glacial period, which ended some 10,000 years ago. Within the last million years, the majority of midwestern United States and much of Canada has been covered at one time or another by an extensive ice sheet. This large continental glacier had a significant impact on the surface features of the area it traveled across. The slow movement of the glacier across the land caused vast quantities of rock and soil that had been frozen in the glacier to be redeposited as drift or till. Drift and till are terms used to describe the debris left behind by a retreating glacier. Gravel, sand, and boulders are examples of glacial drift or till. Some of this drift was deposited into old preglacial river valleys; other drift piled up into belts of hills (terminal moraines) at the edges of the glacier. In South Dakota, the Coteau des Prairies is the largest example of a terminal moraine left behind by a glacier. Along with depositing debris, glaciers also gouged and eroded the land as they moved across.
South Dakota’s topography has been vastly altered by glaciers. The most significant change was in the extent of the drainage system. In preglacial times, there is reason to believe that most of the rainwater or meltwater from snow was quickly carried back to the ocean. Today, much of the precipitation is retained temporarily on the surface in the lakes. Streams meander slowly from lake to lake and carry only a part of the total precipitation away to the rivers. These streams have not been able to fully develop into a network that quickly and efficiently drains. The reason streams have not matured is simply because they have been working to erode the land for only the last 10,000 years--the estimated length of time since the last glacier began its final retreat. Compared to the long history of the Earth, this time span is relatively short.
As glaciers advanced and retreated through South Dakota, some of the ice that stagnated was more difficult to melt than other areas. While these ice chunks were trapped, the glaciers continued to deposit sediments around and sometimes on top of these isolated ice cubes. As the ice blocks slowly melted, they left behind depressions in the landscape. Eventually, these depressions filled with snowmelt and rainwater, which in turn produced kettle lakes.
Kettle lakes can be of any size and their shorelines can be composed of anything from clay to sand to boulders. The majority of lakes in the world are kettle lakes created by glacial activity.
NOT A LOGGING REQUIREMENT: Feel free to post pictures of your group at the area or the area itself - I love looking at the pictures.
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