The Great Barrier Reef

Courtesy of http://www.divethereef.com/Galleries/GBRE1/GBRE1-R-1021.asp

FUN FACTS!!

~ The water in and around the Great Barrier Reef covers and area slightly smaller than the state of Minnesota!

Courtesy of http://library.thinkquest.org/J002388/gbreef.html

~ The Great Barrier Reef is the only living thing on Earth that can be seen from space!

Courtesy of http://teachearth.com/postcard/postcard.htm

~ The Great Barrier Reef hosts 4,000 species of molluscs, 400 species of corals, 215 species of birds, 6 species of sea turtle, and 1,500 species of fish!

Courtesy of http://www.wildlifebiz.org/bright_ideas/113.asp

~ Parts of the Great Barrier Reef are more than 18 million years old!

Courtesy of http://www.wildlifebiz.org/bright_ideas/113.asp

~ The Great Barrier Reef, supports a $640 million dollar tourism industry!

Courtesy of http://www.coralprincess.com.au/German/page4-g.htm

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Photos courtesy of http://www.psrc.usm.edu/macrog/sea/coral.htm

The Great Barrier Reef

Introduction:

The Great Barrier Reef lies off the northeastern coast of Australia in the Coral Sea (in the Pacific Ocean). At 1,250 miles long, the Great Barrier Reef is the largest coral reef in the world consisting of a series of more than 2,800 smaller reefs. It forms a natural break water between the Pacific Ocean and the mainland, as well as providing a home for thousands of different species.

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Geologic Processes + Products:

What is the history of it's formation?

20,000 years ago when Australia was developing, the sea flooded the coastal plain as the world was emerging from the most recent ice age. The sea level around the Australian coast was then about 120 meters lower than it is today. The mountain range along the coast was previously separated from the sea by a coastal plain, dotted with hills. As sea level rose, coastal plains gradually became flooded. The hills that had become islands became fringed with coral, and eventually were completely covered after being submerged due to the rising sea level. Corals and reefs grow best in moving water, therefore, as the coastal plain became flooded, the most healthy, and abundant reefs lined the outside edge of the old coastal plain.

Cross section of coastal north Queensland 20,000 yrs. ago

Cross section of coastal north Queensland 13,000 yrs. ago

Cross section of coastal north Queensland presently

Images courtesy of http://www.aims.gov.au/pages/research/project-net/reefs/apnet-reefs00.html

How is it that it could have lasted so long?

The Australian platform has a very stable geological setting. Coral cannot survive at temperatures below 21° Centigrade, therefore, the warm waters of the Australian continental shelf provide a desirable, constant environment for such an ecosystem. Also, the southeast tradewinds batter the outer edge of the reef for 9 months of the year which keeps the reef supplied with fresh seawater (needed for its nutrients which help coral grow).

What different types of reefs does it consist of?

Barrier Reef- A barrier reef grows some distance from the shore and has a lagoon which separates the reef from the shore.

Platform Reef- Platform reefs are oval and occur when coral formations build up on shallow areas in the open sea. They often hold very shallow lagoons.

Fringing Reef-Fringing reefs are usually narrow and form an adjacent border to a shorline. These are commonly found inside barrier reefs.

Images courtesy of http://www.starfish.ch/reef/reef.html

How does a coral reef form?

Coral reef formation is an extremely slow process with corals growing only a few millimeters per year. As sea levels rise and fall, coral forming on continental shelves and islands die and cement together creating a growing place for newer corals. Once a reef reaches sea level, it will continue to grow horizontally.

Image courtesy of http://www.jochemnet.de/fiu/OCB3043_39.html

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Impacts

The Great Barrier Reef is it's own ecosystem, hosting thousands of types of coral, animals, and plants. Not only does the geological setting of the area stable, it also is one of Earths great natural wonders. Thousands of tourists visit the reef every year to admire it's wonders and beauties. Unfortunately, people weren't always careful and knowledgeable about the fragility of reefs, so much coral was damaged through human contact and pollution. Today there is much work to try and save the reefs from dying off and to prevent further damage by humans. However, much of it still remains healthy and beautiful, and I hope that we can keep it that way.

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Literature Cited

Dakin, William J. Great Barrier Reef. Melbourne, Australia: Australian National Publicity, 1950

Davis, Willam M. The Coral Reef Problem. New York: American Geographical, 1928

http://www.reef.crc.org.au/aboutreef/coral/coralgbr.html

http://www.environnement.gouv.fr/ifrecor/domtom/typesoa.htm

http://www.lpi.usra.edu/publications/slidesets/geology/sgeo/slide_10.html

http://www.greatbarrierreef.org/

http://www.aims.gov.au/pages/research/project-net/reefs/apnet-reefs00.html

http://library.thinkquest.org/J002388/gbreef.html

http://www.nationalgeographic.com/earthpulse/reef/reef1_flash.html

Link to other Student Webpages for 2004 Earlham Physical Geology

Copyright © 2004 Earlham College. Revised April 30, 2004 . Send corrections or comments to larkiph@earlham.edu larkiph@earlham.edu