[Coral-List] Backstepping Coral Reefs

Eugene Shinn eugeneshinn at mail.usf.edu
Tue Oct 17 12:47:47 EDT 2017

Good to see that hurricane-induced backstepping is not limited to 
Florida, (see Blanchon et al., 2017,_Retrograde accretion of a Caribbean 
fringing reef controlled by hurricanes and sea-level rise._) Thank you, 
Paul. I also thank Joseph Pawlik and Vassil Zlatarski for posting Reefs 
of the Past: Videos of coral reefs of Florida Keys (1987) and Cuba 
(1970s) in coral-list vol. 110, issue 7. Also see 
https://www.youtube.com/watch?v=LIbmsHmuxWk&feature=youtu.be  that shows backstepping at Grecian Rocks. John Halas shot the segment 
that shows the backstepping illustration based on a transect of cores 
across Grecian Rocks.

Our first hint that traditional textbook illustrations of reef 
accumulation were different from what we see in the Holocene came with 
passage of Hurricane Donna in 1960 (Ball et al., 1967). Similar effects 
were also observed after Hurricane Betsy in 1965 (Perkins and Enos, 
1968). In those days, we lacked technology for coring coral reefs. We 
simply noted that many large head and branching corals from the seaward 
side of Florida reefs had been transported and deposited on the landward 
side of reefs. What we saw also explained the small coral-debris islands 
on the landward side of many Florida Keys reefs. Thanks to MacIntyre and 
Glynn (1976) we were all provided with the long-needed reef coring 

Our very first test of our diver-operated core drill at Long Reef in the 
upper Keys indicated backstepping (Shinn et al., 1977). Later, we 
demonstrated backstepping at Carysfort Reef. Next was Grecian Rocks as 
shown in the Grecian Rocks Reef video mentioned above. Since then, we 
have seen backstepping in all the major reefs in the Florida Keys except 
for Southeast Reef at Dry Tortugas, which showed both outstepping and 
backstepping. Yes, hurricanes taught us a lot about reef growth and 
geologic processes in the Florida Keys. The geologic effects of rising 
sea level and repeated storms during the Holocene is one of the main 
themes in our new book, /Geology of the Florida Keys /(Shinn and Lidz), 
due out in February 2018 (University Press of Florida). The book is 
dedicated to the memory and teachings of Robert N. Ginsburg, who 
launched so many of us on our geological careers.Gene


Ball, M.M., Shinn, E.A., and Stockman, K.W., 1967, The geologic effects 
of Hurricane Donna in south Florida. /Journal of Geology/, v. 75, p. 

Macintyre I, G, Glynn P. W., 1976, Evolution of a modern Caribbean 
fringing reef, Galeta Point, Panama. Am Assoc Petrol Geol Bull 60, pp 

Perkins, R.D., and Enos, Paul, 1968, Hurricane Betsy in the 
Florida-Bahamas area – geologic effects and comparison with Hurricane 
Donna. /Journal of Geology/, v. 76, p. 710-717.

Shinn, E.A., 1980, Geologic history of Grecian Rocks, Key Largo Coral 
Reef Marine Sanctuary: Bulletin of Marine Science, v. 30, no. 3, p. 646-656.

Shinn, E.A., 1988, The geology of the Florida Keys: Oceanus, v. 31, no. 
1, p. 47-53.

Shinn, E.A., 2011, Spurs and Grooves, In: Encyclopedia of Earth Sciences 
series, /Encyclopedia of Modern Coral Reefs, Structure, Form and 
Processes/, David Hopley editor, Springer, p. 1032-1034.

Shinn, E.A., Halley, R.B., Hudson, J.H., and Lidz, B., 1977, Topographic 
control and accumulation rate of some Holocene coral reefs — South 
Florida and Dry Tortugas: International Coral Reef Symposium, 3rd, 
Proceedings, Miami, Florida, v. 2, Geology, p. 1-8.

Shinn, E.A., Hudson, J.H., Robbin, D.M., and Lidz, B., 1981, Spurs and 
grooves revisited — Construction versus erosion, Looe Key Reef, Florida: 
International Coral Reef Symposium, 4th, Manila, Philippines, 
Proceedings, v. 1, p. 475-483.

Shinn, E.A., and Jaap, W.C., 2005, Field guide to the major organisms 
and processes building reefs and islands of the Dry Tortugas: The 
Carnegie Dry Tortugas Laboratory:

SE Geological Society.

Shinn, E.A., Lidz, B.H., Kindinger, J.L., Hudson, J.H., and Halley, 
R.B., 1989, Reefs of Florida and the Dry Tortugas, a guide to the modern 
carbonate environments of the Florida Keys and the Dry Tortugas: Field 
Trip Guidebook T176, 28^th International Geological Congress, American 
Geophysical Union, Washington, D.C.


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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