Hatchie River's OXBOW- HART LAKE EC** EarthCache
Hatchie River's OXBOW- HART LAKE EC**
-
Difficulty:
-
-
Terrain:
-
Size: 
(other)
Please note Use of geocaching.com services is subject to the terms and conditions
in our disclaimer.
As an EarthCache, there is no 'container' to find, instead you learn something about the geology of the area. This EarthCache is located in the Hatchie National Wildlife Refuge. This Earthcache is accessable by dirt road EXCEPT in the spring when the water is high. The gates are closed when it is unsafe to enter this area. TURN ONTO THE DIRT ROAD SOUTH OF THE BRIDGE on the west side. Go down the road a short distance and turn onto the first road to the left.
To receive credit for this find, simply answer the following questions and submit your answers to my profile. PLEASE SUBMIT YOUR ANSWERS VERY SOON AFTER YOU LOG YOUR FIND OR I MAY NEED TO DELETE!
**This is a SEASONAL EarthCache- Spring FLOODING--the road to it will be closed !
REQUIREMENTS:
1- What are three events that help an oxbow lake form quickly?
2- This oxbow lake does not dry up because of the spring flooding. There are obvious water marks on the Cyress trees standing in the lake. How high does the water rise in the spriing from its summer/fall level?
3- Estimate the width of this lake from where you stand.
4- How many Cyress trees do you see standing in this oxbow lake?( Radis of 100 feet)
* * * * * * * * * * * * * *
The Hatchie Nationall Wildlife Refuge includes over 9,400 acres of bottomland forest which functions as a natural forested woodland, much as it did in Pioneer times. The bottomland forest still slows raging flood waters, filters sediments to improve water quality, and produces immense amounts of timber.
The Hatchie Scenic River is the last unchannelized river of its type in the Lower Mississippi River Valley, but this river is currently experiencing one of ther highest sedimentation rates of any river. Nineteen million tons of sediment per year is being deposited into the 1,400,000 acre Hatachie River drainage system.
GEOLOGY:
An oxbow lake is the result of a long geological/river process that is dependent on several factors:
1- Low slope (the elevation of the river that the "oxbow" was once a part of is not dropping very quickly).
2- The riverbanks are relatively easily eroded as the river cuts into the banks.
3- Time ! (or #4)
4- At times a larger event, such as an earthquake, flood, volcano (out west) or dam (human or natural occuraance) can trigger an oxbow lake overnight by diverting water to a new riverbed.
Lets go into detail: In these areas of low slope (elevation not dropping very quickly), the path of the river begins to wander back and forth creating meanders, or curves. Along each curve, the flow of the river is constantly eroding the outside bank of the meander, while at the same time depositing material on the on the inside.
This is because the area of fastest flow in the river is forced to the outside bank on the curves and the slowest flow is on the inside. Faster water carries more sediment causing the erosion. The slower water is unable to carry as much sediment, so some sediment drops out of the water. The result is a steep bankk on the outer edge of a meander and a gentle slope on the inner edge.
Over time, these meanders get larger and more pronounced as the outer edge is eroded away and the inner edge has material deposited on it. Given enough time, the pronounced oxbow meander gets so curvy that it bends back and touches iteslf creating an oxbow lake.
Remember, water always desires to get "downstream" as fast as possible, and when going "straight through" the neck of what was once a LARGE AND SLOW curve proves advantages (especially if encouraged by one of the larger events mentioned above), the river can literally "abandon" the complete bend, leaving a lake that was once part of the main river.
Most "abandoned" oxbow lakes dry up in time, but this oxbow lake is flooded each spring by its parent river.
Additional Hints
(No hints available.)