[Coral-List] Chris Hind, Fertilizing the ocean-disillusionment

Gene Shinn eshinn at marine.usf.edu
Fri Oct 12 15:01:29 EDT 2007

Dear Chris,  That is not chelated iron being used in the Redlands 
agricultural area west of Miami. The area is naturally red because of 
a thin accumulation of African Dust that contains iron.  That is the 
reason it has been such a productive agricultural area in the first 
place.  You can find the same stuff all over the Caribbean and 
Florida Keys. In San Salvador,  way out in the eastern Bahamas, it is 
called Pineapple loam and without it there would be little 
agriculture there. It is also the red soil in potholes all over the 
Bahamas (and the Florida Keys) where they are called banana holes. 
Pre Columbian pottery on San Salvador was made from African dust 
scraped off the lime rock. It contains just enough clay minerals to 
be fired and made into pottery. Clay minerals do not occur in the 
bahamas unless delivered by the wind. The Florida Keys are covered 
with caliche crusts containing African dust and if you drill down 
about 30 ft you will find a more extensive layer of red caliche 
containing African dust iron. This extensive layer (we call it the Q3 
unconformity) accumulated when sea level was about 300 ft below 
present and the reef tract was dry land. That layer has also been 
correlated with dust layers in Greenland ice cores. (Multer et al 
2002). There is a nice display of this caliche put together by Gray 
Multer at the Windly Key Fossil Reef State Park.
     There are 5 major unconformities  capped with red brown caliche 
in the first 100ft of limestone below the Florida Keys. The were the 
result of previous periods of climate change and  they are the 
markers that allow us geologists to know where we are when we drill. 
The most recent layer on the present surface of the Keys started 
forming about 5,000 years ago according to Carbon 14 dating (Robbin 
and Stipp 1979) and it is still forming. It even contains elemental 
mercury (not published) that predates  power plants in the us. 
Mercury is mined in North Africa along with phosphate (which also 
contains uranium and lead-210) and yes, phosphate and and iron along 
with copper and aluminum has been accumulating preferentially in 
central Florida Bay but that's another story.  It is rewarding  to 
see so many people on the list  agreeing that iron seeding would not 
be good for coral reefs and other ecosystems. That is worth knowing 
when you realize that 1 billion tons of African dust containing 
approximately 5% iron is dispersed in the Atlantic and Caribbean 
basin each year. Remember the peak years for dust flux were 1983 and 
1984  (Shinn et al 2000)
     As for Mt. Trashmore (Black Point landfill) you are correct. 
About 20 years ago we installed 4 monitoring wells adjacent to the 
land fill. The results are published in a Park Service yearbook.  We 
found that the  landfill " juice" that seeps into the underlying 
limestone contains pesticides, plasticizers, and high levels of 
ammonium. The Q3 unconformity, mentioned above, is 17 ft below the 
surface adjacent to the land fill and it is so dense it prevents 
downward passage of  land fill "Juice." The juice therefore flows 
horizontally in a very permeable layer just above the Q3 unconformity 
toward Biscayne Bay. Because of our finding the operators dug a 
trench (down to the top of the Q3) around the landfill to contain the 
      As for the "raping" of gorgonians in the Keys I believe if you 
investigate further you will find that they are growing on permitted 
areas of rock that was placed there by marine life collectors. In 
addition one well known collector grows them under lights under his 
home. You might want to check on that before you sound off.
     I must admit that a lot  of what you say about keys attitudes is 
correct. It is a strange and wonderful place first colonized by 
people running away from government control and were for many years 
more closely allied to Cuba than to the US. World war II changed 
that. The anti establishment anti government mind-set is still alive 
among the original keys residents. I can say this because I was born 
in Key West back when children were propagated there. Gene

Robbin, D. M., and Stipp, J. J., 1979, Depositional rate of laminated 
soilstone crusts, Florida Keys. Journal of Sedimentary Petrology, v. 
49, pp. 0175-0180.
  Shinn, E.A., and Lidz, B.H., (1988), Blackened limestone pebbles: 
fire at subaerial unconformities, in Choquette, P.W., and James, 
N.P., eds., Paleokarst Systems, Characteristics and Significance: 
Springer-Verlag, N.Y., p. 117-131.
Multer, H. G., Gischler,  E., Lundberg J., Simmons, K. R., Shinn, E. 
A., 2002, Key Largo Limestone Revisited: Pleistocene Shelf-edge 
Facies, Florida Keys, USA. FACIES, vol 46 p.  229-272.
Shinn, E.A., Smith, G.W., Prospero, J.M., Betzer, P., Hayes, M.L. 
Garrison, V., Barber. R.T., 2000. African Dust and the Demise of 
Caribbean Coral Reefs.  Geol. Res. Lett. 27, 3129-3032

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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