[Coral-List] Definition of the Great Barrier Reef

Eugene Shinn eshinn at marine.usf.edu
Tue Oct 16 13:31:06 EDT 2012

Thanks Ashley, Little wonder why the geography and geometry of the 
GBR is so confusing to and outsider.  You might be interested to know 
that for the past 60 or more years the Australian GBR has served as 
the model for the Lower Cretaceous Edward reef trend (also called 
Stuart city trend) that circumscribes the northern Gulf of Mexico. 
Geologists working on the Edwards reef trend, as I once did, 
generally refer mainly to the narrow outer barrier of the GBR as the 
modern model. The Edwards trend is often studied where it is exposed 
in uplifted parts of Eastern Mexico. From there the reef  extends 
northward where the trend lies beneath southern Texas at a depth of 
around 16,000 ft. In places it is more than 1000 ft. thick and is an 
oil and gas-producing reservoir. The reef trend is around 12,000 ft. 
beneath Louisiana where it curves southward under western Florida and 
extends beneath the Everglades, and beyond. In Florida it is known as 
the Sunniland trend. Oil was discovered in the reef trend near the 
town of Sunniland in 1943. There are presently about a dozen small 
producing oil fields in south Florida producing form the Sunniland 
reef trend south east of Ft. Myers, Florida.  Most Floridians have no 
idea it is there.  Like the GBR, there are patch reefs in paleo 
landward positions behind the Edward reef barrier. Most are composed 
of Rudistids and corals however I once spent a few weeks studying a 
patch reefs exposed on the Blanco River in the Hill country of Texas. 
That reef contained large coral heads we called Montastrea sp. 
because they looked identical to the modern genus. 
     I write this to explain why geologists have long been so 
interested in the geometry, and conditions under which modern coral 
reefs serve as models for understanding ancient coral reefs. Even 
before Oil and gas was discovered in ancient reefs it was mainly 
geologists who studied coral reefs in Florida. The famous ones were, 
T. Wayland Vaughan, and Alexander Agasssi. In the early 19 hundreds 
geological knowledge was needed for the installation of offshore 
lighthouses to guide and protect shipping from coral reefs.  At that 
time lighthouses were not erected to protect coral reefs. For all 
these reasons the definitions of what constitutes a reef have been 
endlessly discussed at geological conventions ever since I can 
remember.  Biologists did not begin dominating the study of coral 
reefs until the mid 20th century although much biological study of 
individual corals had been initiated by Mayor, Young, and Wells, a 
few decades earlier. We should all thank Jacques Cousteau and SCUBA 
for stimulating and facilitating the abundant biological study of 
modern coral reefs we see today. 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
<eshinn at marine.usf.edu>
Tel 727 553-1158---------------------------------- 

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