[Coral-List] Florida Bay sands

[Martin Moe]

This is a note to Gene Shinn, but I thought I’d post
it on Coral List in case there is a general interest.
I live on Lower Matecumbe Key in the Florida Keys
right on the beach on the Florida Bay side. Recently,
I was looking for a sand substrate for an aquarium
system and checked out the sand available in my area.
There is a sand bar that has developed in the last few
years about 100 feet off the beach.  The bar is about
50 feet wide, over a 100 feet long and over 2 feet
deep. It has moved about 200 feet to the south
covering grass beds and shallowling the water from
about 4 feet to 1 foot in last 3 years. This bar is
evidently a part of a much more extensive sand bank
that extends about a half mile northward. I examined
various sand substrates microscopically looking for
the best grain composition and size for my
application, and was surprised to fine that this bar,
and presumably the more extensive sand beds to the
north, was entirely composed of oolitic sand with
smooth ovoid grains in the approximate range of 100
microns. Although the sand at the wave wash area on
the beach contains many shell fragments, the sand on
the bar has none, it is, evidently, composed only of
oolitic sand. So I wonder, Gene, is this sand in the
process of being formed in Florida Bay, perhaps do the
interaction of Bay and ocean water, something similar
to the Bahamas muds, or is simply a sorting and
movement of sediments in the shallow waters of the
Bay? And if oolitic sand is being formed, what effect,
if any, will the restoration of water flows through
the Everglades have on sediment formation in the Bay?
Just curious….

Martin Moe