Oxbow lake Siikauopaja EarthCache
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Welcome to one of the Siikauopaja Oxbow lakes along the Oulanka River.
An oxbow lake is a U-shaped body of water formed when a wide meander from the main stem of a river is cut off to create a lake. This land-form is called an oxbow lake for the distinctive curved shape that results from this process.
An oxbow lake is formed when a river creates a meander due to the river eroding the banks through hydraulic action and abrasion/corrosion. After a long period of time this meander becomes very curved, and eventually the neck of the meander will touch the opposite side and the river will cut through the neck, cutting off the meander to form the oxbow lake.
The curved path of a river around a bend causes the surface of the water to be slightly higher on the outside of the river bend than on the inside. As a result, at any elevation within the river the water pressure is slightly greater near the outside of the river bend than on the inside. There is a pressure gradient toward the convex bank which provides the centripetal force necessary for each parcel of water to follow its curved path. The boundary layer flowing along the floor of the river is not moving fast enough to balance the pressure gradient laterally across the river. It responds to this pressure gradient and its velocity is partly downstream and partly across the river toward the convex bank. As it flows along the floor of the river it sweeps loose material toward the convex bank. This flow of the boundary layer is significantly different from the speed and direction of the primary flow of the river, and is part of the river's secondary flow.
There are several Oxbow lakes along the Oulanka but this Siikauopaja is one of the best known and also one with a beautiful U-shape. This lake and several other Oxbow lakes is now part of the Natura nature conservation program.
To log your find you must visit the location and complete the following tasks:
- Estimate the difference on the water level between the lake and the river. Send this information to the cache owner.
Optional challenge:
- Take some pictures and add them to your log.
You don't need to wait for a permission to log the cache.
Have fun and feel free to share your experiences about your journey.
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Treasures
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