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Characteristics of a Meandering
Channel
Meandering
streams spread out in low-relief valleys or in low-relief coastal
plains. Water flows in a definite channel tending to meander, or
not flow in a straight line.
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Meandering
channel |
As meanders
(bows) form, they influence the flowing water to cause more
meandering. The reason for this is that the main force of the river
ends up colliding with the outer bank when it reaches a bow. The
force of the water erodes into this outer bank (called the "cut
bank") causing the meander to extend outward. At the same time the
water rolls in a circular motion starting at the cut bank and
rotating downward toward the bottom of the channel. It then flows
toward the inside bank and then back up to the surface. This causes
sediments eroded from the cut bank to be deposited on the inside
bank, known as the point bar. It also results in the channel being
deeper on the outer cut bank than on the inner point bar.
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Effect of a curved channel
on water flow |
The process
of meandering may continue until one meander comes in contact with
another meander. The river will then take the easiest, more direct,
path which isolates the previous river channel. This creates a new
body of water, called an oxbow lake, which is separate from the
river's movement. Over time, a river may meander in many ways,
leaving sedimentary deposits and oxbow lakes throughout a
valley.
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Channel shifting over
time |
To claim a find for this Earthcache,
you must meet the following four requirements:
1. Post a picture of
you and/or your GPS with a section of the meandering channel in the
background.
EMAIL ME WITH THE FOLLOWING INFORMATION
(DO NOT include this in your online post):
2.
Indicate what plant growth exists on the flat plain along the
channel.
3. Take
special note of the number of bows (perhaps make a drawing) and
choose the best sketch (A, B or C) from the below diagram to
indicate the best match in shape of the meandering channel as it
currently exists between Reference point #1 and Reference point #2
(the 2 bridges).
4.
Describe the earth materials in the sediment that is being eroded
(of what does it consist?).
If you do not meet all of the
requirements your log will be deleted.
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