Dating the Great Barrier Reef

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Science  25 May 2001:
Vol. 292, Issue 5521, pp. 1451-1453
DOI: 10.1126/science.292.5521.1451e

Coral reefs are important as marine ecosystems, and their growth has been linked to the carbon dioxide content in Earth's atmosphere. However, the timing of major reef growth has been uncertain for many reefs, including Earth's largest, the Great Barrier Reef of Australia. Analysis by an international consortium of two recent drill cores taken from the Great Barrier Reef indicates that it began to form about 600,000 years ago. This age is based on magnetic stratigraphy through the drill core (and the absence of the marked geomagnetic reversal 790,000 years ago) and on the Sr isotope composition of the corals. This age implies that the Great Barrier Reef has grown by about 10 to 28 centimeters per year, which is similar to the growth rate of other reefs worldwide. Why reef growth started at that time is unknown, but it might reflect a period of increased sea surface temperatures, a connection with atmospheric carbon dioxide levels, or both. — BH

Geology29, 483 (2001).

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