A short trail in the Sand Dunes State Forest will lead you to this earthcache spot. Here you will be standing on one of many forested sand dunes that are a part of the Uncas Dunes. These dunes are actually a series of low hills in a rolling terrain. The dunes were named after the endangered Uncas Skipper, a butterfly that occurs over a large range of North America, but its occurrence in Minnesota is restricted to this location in Sherburne County. In addition to the Uncas Skipper, biological surveys in the last 20 years have discovered 10 additional rare animal species and 8 rare plant species whose habitat needs are tied to the rare sand dunes ecosystem.
Twenty thousand years ago, a great sheet of ice, the Superior lobe, covered this area. At its farthest advance, it formed the St. Croix moraine, a series of high hills to the west, south, and east. When it melted, it left behind vast deposits of gravel, sand, and clay. After the Superior lobe retreated, another glacier, the Grantsburg sublobe, moved in from the southwest, filling the lowlands with ice. Again the climate warmed, melting the ice and creating a lake (long extinct glacial Lake Grantsburg) that covered most of this area – including this spot. Fine sand carried in the meltwater settled to the bottom. The lake disappeared when its water found an outlet into the Mississippi River, leaving the Anoka Sand Plain, an expanse of sand measuring 850 square miles. Beginning about eight thousand years ago, drier weather and wind formed sand dunes in parts of the Anoka Sand Plain, including in the area where you are now standing. Outside this area, the original dunes on the Anoka Sand Plain have been largely destroyed by reshaping and disturbance associated with housing development.
Pines and other evergreens were planted throughout the dunes since the 1930’s and the Sand Dunes State Forest was created in 1943. Currently, 5675 acres are owned by the state with 2700 acres of pine plantations. The Sand Dunes State Forest is still a working forest producing wood products. A variety of recreational activities such as hiking, horseback riding, camping, and cross-country skiing is available here. There are 18 miles of multi-use trails.
To get credit for this earthcache, email the answers to the following questions to my Geocaching Profile page:
- Describe the color and texture of the sand on the trail in front of you.
- Take the elevation reading at this spot and at the parking lot. What is the height of the dune you are standing on?
- How did the Uncas Dunes form?