The location:
Welcome to the Upper Souris National Wildlife Refuge that is located about 30 miles northwest of Minot, North Dakota. The Refuge straddles 35 miles of the picturesque Souris River valley in northern North Dakota. The Souris River basin figures prominently in the cultural and natural history of the North American mid-continent plains and prairies.
The Upper Souris National Wildlife Refuge, or NWR, was established in 1935 "...as a refuge and breeding ground for migratory birds and other wildlife..." The Refuge habitat is managed for diversity to provide the life requirements of all wildlife. Grasslands are periodically grazed, hayed, burned and rested to provide good nesting and escape cover for wildlife and to rejuvenate the vegetation.
Geology:
One of the unique areas in the NWR is the Oxbow. The dictionary describes an Oxbow as a crescent-shaped lake (often temporary) that is formed when a meander of a river is cut off from the main channel.
An Oxbow is formed when a river cuts through a meander neck to shorten its course, causes the old channel to be rapidly blocked off, and then migrates away from the lake.
When a river reaches a low-lying plain, often in its final course to the sea or a lake, it meanders widely. In the vicinity of a river bend, deposition occurs on the convex bank. Continuous deposition on the convex bank and erosion of the concave bank of a meandering river cause the formation of a very pronounced meander with two concave banks getting closer.
The narrow neck of land between the two neighboring concave banks is finally cut through, either by lateral erosion of the two concave banks or by the strong currents of a flood. When this happens, a new straighter river channel is created and an abandoned meander loop, called a cutoff, is formed. When deposition finally seals off the cutoff from the river channel, an oxbow lake is formed.
Eventually, oxbow lakes are silted up to form marshes and finally meander scars, marked by different vegetation or the absence of cultivation. The lakes commonly are filled with clay-sized sediment that is less easy to erode than surrounding material and thus may cause a more complex meandering system in its parent stream.
*** Please take out what you bring in. We want to keep the area clean for all! Please park your vehicle in the designated area. Don’t park on the side of the road. Please do not leave the paths! You can find the rules and regulations at the visitor center. Please respect the refuge!***
In order to count this Earthcache as a find, you must complete the following tasks and (using the message the owner function) email the answers to me.
1: Based on your observations of the site, and in your own words, explain the process of erosion that produced this oxbow lake.
2: Based on your observations, please describe how the feature at N 48 27.211 W 101 34.606 was formed.
Not Required to Log: We would love to see your photos of the area!!
Sources:
http://www.fws.gov/refuge/upper_souris/about/about_the_complex.html
http://www.britannica.com/science/oxbow-lake
http://www.mbgnet.net/fresh/lakes/oxbow.htm
http://www.thefreedictionary.com/oxbow+lake