Coteau des Prairies EarthCache
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In order to count this earthcache as a find, you must complete the following tasks and email the answers to me. 1. What evidence do you see at this site that indicates a glacier passed through this area? 2. Describe the landscape you see east of this location. 3. What is the elevation of the Coteau des Prairies at this location? (fun fact: the elevation at the base of the plateau is about 960 feet) This earthcache is located at the Wilmot rest area (exit 213), along the northeastern edge of the Coteau des Prairies. The rest area can be accessed by those traveling north or south along I-29 as well as those traveling along highway 15. The Coteau des Prairies (or “hills of the prairie”) is a plateau that rises from the prairie flatlands and stretches about 200 miles from north to south and 100 miles from east to west. It covers much of eastern South Dakota, southwestern Minnesota, and northwestern Iowa This plateau is one of the most conspicuous landforms of the US midcontinent that can be seen on a relief map. Shaped like a flat iron, the plateau received its name from early French explorers from Quebec, a French speaking province. “Coteau” is the French word for “slope.” The plateau is composed of thick glacial deposits, which were the remnants of many repeated glaciations. Beneath the glacial deposits is a small ridge of resistant Cretaceous shale. (Shale is a sedimentary rock that is formed from clay that is compacted together by pressure. Shale is used to make bricks and other material that is fired in a kiln.) Another type of deposit found on the plateau is pipestone. Pipestone (a brownish-red mineral) has been quarried for hundreds of years by Native Americans, who use the mineral to make sacred peace pipes. One of these quarries is located at Pipestone National Monument near Pipestone, MN, which is also located on the Coteau des Prairies. 20,000 years ago, a massive glacier carved out the plateau. During the last ice age, two lobes (tongue-like extensions of the main ice sheet) of the glacier parted around the pre-existing plateau. These lobes, the James River Lobe and the Des Moines Lobe, moved south along pre-glacial stream valleys just to the east and west of the plateau. As the lobes moved south, they further deepened the low lying prairies on either side of the plateau, which then drained meltwater as the glaciers retreated to the north. Today, the Coteau des Prairies has not yet been extensively drained and still has numerous small glacial lakes and wetlands. The Big Sioux River in South Dakota and the Cottonwood River in Minnesota work to drain the area. 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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