Come Play in My Sandbox EarthCache
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Size: 
(large)
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Come Play in My Giant Sandbox is another stop on the continuing tour featuring the Geology of the Root River State Trail.
The Root River State Trail crosses the unique landscape of Minnesota’s “Historic Bluff Country,” and provides a birds-eye-view into the processes that have been forming rocks and the land surfaces in southeastern Minnesota during the past 500 million years. Flat lying layers of limestone and dolostone form high bluffs above narrow river valleys, such as the Root River valley. The limestone uplands are farmed. The Root River has eroded a steep-sided valley into the layers of limestone and dolostone.
As you move from west to east on the trail you will be moving down the stratigraphic section-from younger to older rocks. Sandstone beds appearances vary from site to site. This site showcases sandstone that appears like a bottled sand art.
Come Play in My Sandbox formed as near-shore or beach sand at the margins of a shallow sea. As you pick up a handful of the eroded sand from the base, you will notice that it is made of quartz grains, which are all rounded.
The St. Peter Sandstone is a very soft and friable (easily eroded) because this is no mineral cement between the sand grains. The sandstone colors vary immensely due to weathering, the amount and type of minerals from precipitation and oxidation.
The St. Peter Sandstone is medium-grayish color on weathered surfaces, but has more striking whitish to yellow or slightly orange colors where it has been excavated. The horizontal orange, yellow and redlines are liesegang bands, Liesegang bands are colored bands in rock that results from precipitation and oxidation of minerals due to changes in the water table levels. The slightly greenish layers include a small amount of mud, are an original depositional feature.
A thin loess cover covers the giant sandbox cliff. Loess is a loose layer that consists of clay to fine sand that has been transported and deposited by winds.
As mentioned earlier, this site appears like a giant bottle of sand art, with very loose material and beautiful patterns of varying color. Other stops on the tour will include St. Peter Sandstone with different appearance. These sites show sandstones that “harden up” a bit as the sandstone exposure surfaces “case harden” by the relatively recent (and probably ongoing) precipitation of iron oxide and calcium carbonate cements. Because of this surface hardening the St. Peter sandstone beds can be held up in nearly vertical cliff faces.
At this site, examine the sandy surface.
The Root River State Trail area is a prime habitat for the threatened timber rattlesnake.
The trail is owned by the Department of Natural Resources, which encourages the enjoyment of the natural environment, but prohibits the removal of rocks from the trail area.
Tasks:
1-You are in a giant sandbox, tell me about the soil as you traverse closer to the sand pile and along the various levels.
2. What erosion features occur at this site?
3- As you examine the sandy surface and colors, look for “light green paint flakes” . Examine these “flakes”. What components are in the flakes?
4-What mineral creates the yellow, orange to red sandstone? What creates the varying degrees of color?
5- What type of layer is above the sandstone?
6-What is the elevation of the waypoint?
What is the elevation of the additional waypoint? N 43 43.012 W 092 06.456
Email your answers via my profile; please include the earthcache name Come Play in My Sandbox, number in your party, and cachers’ names. One email per caching group.
All earthcaches along the Root River Trail are handicap assessable sites, except during snow cover season. If you have a physical disability, which prohibits you from accessing this earthcache from the trail, credit will be accepted per abilities to obtain information
All information for this series of earthcaches along the Root River State Trail is from the following listed source:
Mossler, J.H., 1999, Geology of the Root River State Trail Area, Southeastern Minnesota: Minnesota Geological Survey Educational Series 10, 56 p., 1 map in pocket.
Available from:
Minnesota Geological Survey
2642 University Avenue West
Saint Paul, Minnesota 55114-1057
Web site: (visit link)
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