In order to count this Earthcache as a find, you must complete the following tasks and email the answers to me.
1. What is the elevation at the parking area?
2. Describe the area you see.
3. Estimate the height of the hills.
This Earthcache is located at the Hidewood rest area along I-29. The cache is only accessible to those traveling northbound on the interstate; however, the views of the glacial debris can be enjoyed by travelers going either direction. The last of the great glaciers entered northeastern South Dakota about 20,000 years ago. The region was covered by colossal sheets up ice up to three miles thick. These gigantic glaciers gouged and sculpted the landscape, scooping out valleys and creating boulder-strewn hills. When the last glaciers retreated northward only 12,000 years ago, they left behind a landscape of unusual beauty. These glaciers had a profound and lasting effect on South Dakota’s geography. Today, the evidence of the ice ages can still be seen in South Dakota’s Glacial Lakes Region--especially in its contrasting terrain.
Here, I-29 passes over some of the oldest glacial drift in the state. The hills in this area were some of the first to be laid down by the Wisconsin glaciation period. The Wisconsin Ice Age is the most recent ice age to have occurred. There were several different episodes of glaciation throughout this period. The debris in this area managed to avoid being buried by further glaciation mainly due to its high elevation. Scattered stream valleys, mostly filled with gravel, cut the gently rolling surface of the land throughout the glacial era. These streams carried huge volumes of meltwater away from the ice fronts as the glaciers rapidly melted at the end of the ice age. As the streams carried water away from the ice sheet, they further carved out the land and helped shape it into the sight you see today.
The till plain you are looking at occupies a narrow strip along the central part of the Coteau des Prairies. The Coteau des Prairies, or Prairie Hills, is the most prominent geological feature in northeastern South Dakota. It is a plateau that extends a little over 200 miles from north to south and is 100 miles wide at its maximum width. The plateau extends into southwestern Minnesota and northwestern Iowa. The Coteau des Prairies is a composed of the remnants of many repeated glaciations. So much debris has piled up here that the plateau has a composite thickness of approximately 900 feet. This land feature was carved out during the last ice age when the main ice sheet spilt at the tip of the pre-existing plateau and continued its course south on either side of the plateau. This further deepened the lowlands flanking the plateau and accentuated the height of the plateau itself.
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.