[Coral-List] Lower Keys ooids

[Martin Moe]

Dear Gene,
I'll be more than happy to send you a sample of the
sand, I'll send a container with wet sand and a
container with air dried sand. I won't sieve or wash
the samples so you can see everything that I collect.
Of course I have no idea if the sand is composed of
true ooids or Halimeda sands, but it will be
interesting to find out. I didn't take a sample today,
the tide was high this afternoon (full moon) and a
stiff west wind was kicking up two foot waves. I would
have gotten cold and wet... I guess I'm getting soft
in my old age. 

Martin 

--- Gene Shinn <eshinn at marine.usf.edu> wrote:

> Dear Martin,  Of course I would love to have a
> sample of the ooid 
> sand you described. I am a little suspicious that
> they may not be 
> true ooids, at least in the Bahamian sense. Many
> geologists have 
> called the sands on White Banks off Key Largo ooids
> but they are 
> mainly just polished ovoid-shaped Halimeda sands
> with a superficial 
> oolitic coating. The water at white banks is far
> more similar to 
> water on the Bahama banks where ooids are forming
> than water in 
> Florida Bay. One of the great mysteries  is why we
> have not found 
> real ooids anywhere in the Florida Keys before.  For
> example, the 
> tidal currents currents and bed forms on the
> "Quicksands," west of 
> the Marquesas, are exactly like those in the ooid
> forming areas of 
> the Bahamas. The difference is that the sands are
> 90%  Halimida 
> flakes and there are no ooids.  We really looked for
> them. The large 
> submarine sand dunes move back and forth several
> meters with each 
> tidal change just like ooid sands in the Bahamas.
> The major visual 
> difference is the water is green and visibility is
> seldom greater 
> than 30 ft if that much. The  Pleistocene limestone
> underlying the 
> Quicksands, however, is oolite. So for unknown
> reasons ooid sands 
> were forming  during the Pleistocene, (when sea
> level was 20 feet 
> higher than today) and creating the tidal sand bars
> that became  the 
> lower Florida Keys of today. Ooids also formed and
> created beaches 
> that are now 300 ft below present sea level off the
> keys. They formed 
> during lowered  sea level  during the last glacial
> period about 
> 10-18ka.  So there are still some great mysteries 
> to be solved. If 
> you have true ooids forming off your dock that would
> really be 
> something. Please send sample to address below. Best
> Wishes, Gene
> -- 
> 
> 
> No Rocks, No Water, No Ecosystem (EAS)
> ------------------------------------
> -----------------------------------
> E. A. Shinn, Courtesy Professor
> University of South Florida
> Marine Science Center (room 204)
> 140 Seventh Avenue South
> St. Petersburg, FL 33701
> <eshinn at marine.usf.edu>
> Tel 727 553-1158---------------------------------- 
> -----------------------------------
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