On a quiet moonlit night in the year 1890 the British-Indian liner Quetta traveled through the Torres Strait near Thursday Island, north of Australia. Located at the northern end of the Great Barrier Reef, it is the world's most widespread coral reef complex. The ship suddenly hit a reef pinnacle that ripped through most of its hull, and sank within three minutes. Nearly half of the ship's 293 passengers perished. The strait had been carefully charted between 1802 and 1860, and the crew expected no reef where the ship foundered. Some have wondered if possibly a coral reef could have grown rapidly enough between the time of sounding and 1890 to cause the tragedy.1
Coral reefs result from the activity of a variety of organisms that remove lime (calcium carbonate) dissolved in seawater and slowly create the largest structures on earth made by living organisms. Mollusks, foraminifera, and bryozoa can provide substantial amounts of minerals for reef growth. However, biologists consider coral and coralline algae to be the most important contributors.
The rate of coral reef growth is of considerable interest not only because reefs are potential navigational hazards but also because of questions about the amount of time required to build them. Some wonder whether such huge structures could form in a few thousand years, as implied by the biblical model.
The enormous Great Barrier Reef of Australia does not appear to pose a very serious time problem for Scripture. While it is more than 2,000 kilometers long and up to 320 kilometers offshore, drilling operations down through the reef have encountered quartz sand (a nonreef type of sediment) at less than 250 meters2 indicating that it is a shallow structure not requiring a vast amount of time for development. On the other hand, drilling operations on Enewetak (Eniwetok) Atoll in the Western Pacific have penetrated 1,405 meters of apparent reef material before reaching a volcanic (basalt) rock base.3 The rates of growth assumed by most investigators would dictate that it would take at least scores of thousands to hundreds of thousands of years to form a reef this thick. Criticizing the biblical model, one author points out that the Eniwetok reef would have to grow at the rate of 140 millimeters per year to have formed in less than 10,000 years. He states: "Such rates have been shown to be quite impossible."4
Researchers face many problems in determining how rapidly reefs grow. The fact that some estimates are more than 500 times faster than others (Table 1) indicates that we know extremely little about such complex and delicate ecological systems. The sparse distribution of coral in some studies reflects less- than-ideal reef conditions. The best growth rates seem to take place a little below the surface of the ocean.5 Reefs cannot grow above sea level, and re- searchers sometimes use ancient reef surfaces to determine past sea levels. Since sea level limits the growth of reefs, estimates of growth near the surface of the ocean may be strongly influenced by growth-limiting circumstances. Low tides can kill the reef-forming coral by exposing them too long to the air. Silting and pollution from land can also be detrimental. Furthermore, a number of present-day reefs are now dying or dead.6 Less-polluted conditions when earth was not so populated could have favored more rapid growth of the delicate organisms that build reefs.
One must also remember that coral reef growth ceases below a certain depth because of lack of light. Therefore, scientists assume that the volcanic base of Eniwetok Atoll, now 1,405 meters below sea level, would have been near sea level when coral growth began on its surface. The base gradually sub- sided, and coral growth kept up with this.
Some of my graduate students and I have studied reef-building organisms of Eniwetok and several other reef localities to determine how various environmental factors affect growth. A moderate rise in temperature of a few degrees favors more rapid growth, while ultraviolet light at the ocean surface inhibits growth.7 These and other factors can significantly affect rates of reef growth. While some of the hard "brain"-shaped coral and coralline algae grow slowly, the branching forms develop rapidly. A dense concentration (Figure 1) of healthy branching coral growing at optimal rates (second part of Table 1) could create rapid reef growth. Many corals frequently form branches above each other, compounding production rates. The potential is impressive, 10 branches each growing at the rate of 100 millimeters per year and subdividing into three branches each year would result in a total of 59 kilometers of single branches in 10 years.8
A number of investigators have studied rates of coral and coral reef growth. Some estimates appear in Table 1. The top section, entitled "Rates of Reef Growth," derives from observations of reefs as a whole, while the section entitled "Maximum Rate of Coral Reef Frame Builders" represents the fastest rate of growth of those corals that could provide a physical framework for the reef. This framework would also offer protection for other smaller reef-building organisms as well as serving for the entrapment of water-transported sediments. Note that the fastest rates for reefs9 and for framebuilders10 do allow for the growth of the Eniwetok reef, which has a thickness of 1,405 meters, in less than 3,400 years. These fastest rates for reefs are based on soundings, which are the most direct and simple measurements and are probably more reliable than the less-direct methods that give slower growth rates. Such data indicate that the rate of coral reef growth does not present as great a challenge to the biblical concept of creation a few thousand years ago as is sometimes claimed.
1. Ladd HS. 1961. Reef building. Science 134:703-715.
2. (a) Flood PG. 1984. A geological guide to the northern Great Barrier Reef. Australasian Sedimentologists Group Field Guide Series, No. 1. Sydney: Geological Society of Australia; (b) Stoddart DR. 1969. Ecology and morphology of recent coral reefs. Biological Reviews 44:433-498.
3. Ladd HS, Schlanger SO. 1960. Drilling operations on Eniwetok Atoll: Bikini and nearby atolls, Marshall Islands. U.S. Geological Survey Professional Paper 260:863-905.
4. Hayward A. 1985. Creation and evolution: the facts and the fallacies. London: Triangle (SPCK), p. 85.
5. This has been noted by several investigators, e.g.: Hubbard DK, Miller Al, 5caturo D. 1990. Production and cycling of calcium carbonate in a shelf-edge reef system (St. Croix, U.S. Virgin Islands): applications to the nature of reef systems in the fossil record. Journal of Sedimentary Petrology 60:335-360.
6. For some reports, see: (a) Anonymous. 1994. Coral bleaching threatens oceans, life. EOS, Transactions, American Geophysical Union 75(13):145-147; (b) Charles D. 1992. Mystery of Florida's dying coral. New Scientist 133 (11 January):12; (c) Peters EC, McCarty HB. 1996. Carbonate crisis? Geotimes 41 (4):20-23; (d) Zorpette G. 1995. More coral trouble. Scientific American 273(4):36, 37.
7. (a) Clausen CD, Roth AA. 1975a. Estimation of coral growth rates from laboratory 45C-incor-poration rates. Marine Biology 33:85-91; (b) Clausen CD, Roth AA. 1975b. Effect of temperature and temperature adaptation on calcification rate in the hermatypic coral Pocillopora damicornis. Marine Biology 33:93-100; (c) Roth AA. 1974. Factors affecting light as an agent for carbonate production by coral. Geological Society of America Abstracts With Programs 6(7):932; (d) Roth AA, Clausen CD, Yahiku PY, Clausen VE, Cox WW. 1982. Some effects of light on coral growth. Pacific Science 36:65-81; (e) Smith AD, Roth AA. 1979. Effect of carbon dioxide concentration on calcification in the red coralline alga Bossiella orbigniana. Marine Biology 52:217-225.
8. Shinn EA. 1976. Coral reef recovery in Florida and the Persian Gulf. Environmental Geology 1:241-254.
9. Verstelle JTh. 1921. The growth rate at various depths of coral reefs in the Dutch East Indian Archipelago. Treubia 14:117-126.
10. (a) Buddemeier RW, Kinzie RA, Ill. 1976. Coral growth. Oceanography and Marine Biology: An Annual Review 14:183-225; (b) Lewis lB, Axelsen F, Goodbody I, Page C, Chislett G. 1968. Comparative growth rates of some reef corals in the Caribbean. Marine Science Manuscript Report 10. Montreal: Marine Sciences Centre, McGill University.