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University of Hawai'i |
(808) 956-8856 Telephone |
For Immediate Release: |
December 7, 2000 |
Contact: Ken Rubin, assistant professor, Department of Geology and Geophysics,
University of Hawai'i at Manoa, 956-8973; krubin@hawaii.edu
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UH research disputes theory on formation of Lana'i fossil
deposits |
A paper published in Nature today offers evidence to disprove a popular theory on the formation of fossil-containing deposits on Lana'i. The widely cited hypothesis is that these large gravel deposits were formed by one giant tsunami with waves of more than 1,000 feet. Research led by Ken Rubin, assistant professor of geology and geophysics at the University of Hawai'i at Manoa, seems to invalidate this theory. Using new mass spectrometric dates, the paper "Fossiliferous Lana'i deposits formed by multiple events rather than a single giant tsunami" suggests that these deposits were formed by several occurrences.
The paper is one of two by UH researchers in the Dec. 7 issue of Nature. Research for the second paper was led by Meredith Hermosura of the UH Center for Biomedical Research at The Queen's Medical Center and the UH John A. Burns School of Medicine. The team of scientists, which includes UH Adjunct Associate Professor Andrea Fleig and Adjunct Professor Reinhold Penner, discusses "InsP4 facilitates store-operated calcium influx by inhibition of InsP35-phosphatase."
The fossil deposit paper systematically tests the giant tsunami hypothesis by presenting new observations of the geological relationships and age distributions of the clasts solid stones found in a sedimentary deposit within the deposits at Kapiha'a Gully on Lana'i.
"Naturally occurring radioactive isotopes indicated that the gravels contain corals of two main age groups with a high degree of statistically significant geographic and stratigraphic as in sequential layers ordering," Rubin says. "This data suggest the deposits were formed by at least three or four different events that were likely separated by 1,000 to 100,000 years."
Multiple, different-age deposits invalidate the main premise of the "single giant wave" hypothesis, which states that giant tsunami waves, generated by submarine landslides in the Hawaiian Islands, deposited chaotic gravels on the southern slopes of Lana'i and Moloka'i. These deposits bear corals and other fossils, beachrock and basalt. The strongest direct evidence for this theory was the geographic distribution of the Hulopoe gravel on Lana'i and inferred giant bedforms in one locality of the discontinuous deposit. Other circumstantial evidence the soil stripping on slopes above the gravels and arrangement of basalt boulders on high ground between gullies was also used to argue that waves washed about 375 meters up on Lana'i in a single catastrophic event about 105,000 years ago.
Rubin says the paper is significant because it disputes the "single
giant wave" hypothesis, which has been used to explain other deposits
around the world and to suggest that catastrophic tsunamis may have been
common in the past and could occur in the future.
