This is a truly textbook oxbow lake when viewed from above.
Oxbow lakes form when erosion and deposition on opposite sides of
stream meanders cause the meanders to be disconnected from the main
stream. The stream itself continues to follow the path of least
resistance (a straight line), leaving an "oxbow" lake as seen in
the diagram below.
Below is the "Google Earth" view of this earthcache oxbow,
outlined in red, and the main stream from which it originated
marked in yellow.
The original meaning of oxbow is a U-shaped frame forming a
collar about an ox's neck and supporting the yoke (14th century).
Anything resembling the shape of such a collar is also called an
oxbow. In the world of waterways, an oxbow is a
bend—especially an extreme, semicircular curve—in a
river or stream (18th century).
The water in this oxbow at the posted coordinates is orange in
color. This is the result of iron in the water and soil. When
ferrous iron is converted to ferric iron, it becomes insoluble and
precipitates out of the water as a rust-colored deposit. This
process can occur when iron-rich groundwater is exposed to the
atmosphere. If the deposits are slimy and clumpy, iron bacteria
could also be present. Iron bacteria function by oxidizing ferrous
iron into ferric iron. An oily sheen on the water often indicates
the presence of iron bacteria, but microscopic examination would be
the true test for their presence. Iron bacteria are found naturally
in soils and water and are not harmful to humans. Iron oxide
deposits are also not toxic to fish or aquatic life, so there could
be aquatic life in this oxbow. Closer examination of the water
would tell the tale.
Another interesting aspect of this oxbow that it resides in all
four quadrants of a 4-way highway intersection.
To get credit for this earthcache, post a photo of your gps
device with the oxbow in the background, and email me the
following:
1. Is the water in the oxbow flowing or stagnant?
2. What chemical process causes the orange color of the water at
the posted coordinates?
3. Name a species of iron bacteria.
4. What is the approximate width of the oxbow at the posted
coordinates (treeline to treeline)?