[Coral-List] impact of beachrock on beach erosion
Eugene Shinn
eugeneshinn at mail.usf.edu
Tue Aug 12 14:46:08 EDT 2014
Barbara,
I have beat on and cored a lot of beach rock over the years. In the
Persian Gulf it can form in one
or two years and creates natural harbors for fishing villages. And then
there is Bimini where some "alternative thinkers" speculate the
submerged beach rock offshore is the remains of Atlantis. See paper below:
/Shinn, Eugene A., 2009, The mystique of beachrock, International
Association of Sedimentology Special Publication No. 41, 19-28/
True beachrock is especially resistant to erosion, however, in many
places in the Bahamas
beach dunes cemented by calcite can be mistaken for true beachrock.
Percolation or rainwater
causes cementation in beach dunes and because of past sea level rise can
now be found in the
intertidal zone.That rock is often mistaken for true beach rock but is
quite different. It is softer
and easily broken and eroded. However, true beach rock is very hard. If
you go to Loggerhead
Key in the Dry Tortugas you can see extensive layers of intertidal beach
rock still forming along
the west side of the island. The rock there contains water pipes that
were placed in soft intertidal
beach sand for the Carnegie research institute lab back in 1904-1905.
This island most likely
would have been washed away long ago if not for the beach rock armor
that is still
forming. The same can be said for much of the swimming beach at Bimini
in the Bahamas. If
you have true beach rock it probably should not be removed. Gene
--
No Rocks, No Water, No Ecosystem (EAS)
------------------------------------ -----------------------------------
E. A. Shinn, Courtesy Professor
University of South Florida
College of Marine Science Room 221A
140 Seventh Avenue South
St. Petersburg, FL 33701
<eugeneshinn at mail.usf.edu>
Tel 727 553-1158
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