The
path a river takes from its headwaters to the ocean is affected by
a huge number of factors. They range from precipitation rates,
bedrock geology, topography, vegetation, tectonic movement, just to
name a few. Over time these factors will change and the flow of the
river changes with them. Sometimes the entire course of the river
will change. The frequency and magnitude of these changes are of
interest to planners and builders because they need to know the
likelihood of a nearby river changing its course again, threatening
cities and the type of soils they will be building on.
A river channel is the depression through which the water of a
river flows during non-flood conditions. When the flow of a river
changes to a new channel the old channel is considered relict. Over
time these abandoned channels are filled in by flooding and dead
plant material. Even long after the relict channels have been
abandoned, they can be identified by the soils that formed in them,
the change in vegetation that grows in them, and the different
infiltration rates through them.
Thus one of the easiest ways to identify relict channels is on
aerial photographs. On aerial photos these the vegetation and water
content of the relict channels stand out. Below is the aerial photo
of the area. (click on the photos for a larger image or open a google map)
Below that is the same photo with one relict channels pointed out.
Now that you can see the difference, there are actually many relict
channels in the area.
The following map shows the relict channels mapped out by a
university professor.
The road at this point crosses perpendicular to a relict river
channel of the Pascagoula River. Use this area to answer the
logging questions.
Send me a note with :
- The text "GC2EBK2 Relict River Channels of the Pascagoula River
" on the first line.
- The number of people in your group (put in the log as
well).
- Using your gps determine the width of the relict channel
- What features did you use to determine where the relict channel
started and ended.
- How well do you think water percolates through the relict
channel and say why.
The following sources were used to generate this
cache:
- Heinrich, Paul V. 2004. A Review of the
Geomorphology and Geoarcheology of Southern Mississippi. Unedited
draft manuscript.
http://www.scribd.com/doc/29722171/Geomorphology-and-Geoarchaeology-of-Southern-Mississippi-2004