One of the criticisms anti-evolutionists direct at evolutionists is the
rapid origin of life. The first evidence of life is found at 3.8 billion
years which is generally beleived to be only 100-200 million years after the
end of the great meteor bombardment which should have sterilized the earth.
New research may answer that criticism.
Nature 409, 144 - 145 (2001) © Macmillan Publishers Ltd.
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Earth science: In the beginning. . .
ALEX N. HALLIDAY
Grains of the mineral zircon have survived from way back in Earth's history.
Analysis of these grains provides information on the state of our planet as
long as 4.4 billion years ago.
When did the Earth's continents and oceans first form? On pages 175 and 178
of this issue, Wilde et al.1 and Mojzsis et al.2 address the question with
reports of uranium–lead (U–Pb) ages and oxygen isotopic compositions of
extremely old zircon grains. Their results provide evidence that continents
and liquid water were surface features of the earliest Earth. Part of one
grain appears to have formed 4.4 billion years ago: this is the oldest
terrestrial solid yet identified. Although it is unclear how general a
picture a few tiny zircon grains can provide, the results represent a
significant advance in reconstructing Earth's Dark Ages
Life was on earth before 4.4 million years. The claim that evolution couldn’
t have produced life in the few million years after the meteor bombardment
is false.
and
Nature 409, 175 - 178 (2001) © Macmillan Publishers Ltd.
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Evidence from detrital zircons for the existence of continental crust and
oceans on the Earth 4.4 Gyr ago
SIMON A. WILDE*, JOHN W. VALLEY†, WILLIAM H. PECK†‡ & COLIN M. GRAHAM§
No crustal rocks are known to have survived since the time of the intense
meteor bombardment that affected Earth1 between its formation about 4,550
Myr ago and 4,030 Myr, the age of the oldest known components in the Acasta
Gneiss of northwestern Canada2. But evidence of an even older crust is
provided by detrital zircons in metamorphosed sediments at Mt Narryer3 and
Jack Hills4-8 in the Narryer Gneiss Terrane9, Yilgarn Craton, Western
Australia, where grains as old as 4,276 Myr have been found4. Here we
report, based on a detailed micro-analytical study of Jack Hills zircons10,
the discovery of a detrital zircon with an age as old as 4,404 8 Myr—about
130 million years older than any previously identified on Earth. We found
that the zircon is zoned with respect to rare earth elements and oxygen
isotope ratios ( 18O values from 7.4 to 5.0 ), indicating that it formed
from an evolving magmatic source. The evolved chemistry, high 18O value and
micro-inclusions of SiO2 are consistent with growth from a granitic melt2,
11 with a 18O value from 8.5 to 9.5 . Magmatic oxygen isotope ratios in
this range point toward the involvement of supracrustal material that has
undergone low-temperature interaction with a liquid hydrosphere. This zircon
thus represents the earliest evidence for continental crust and oceans on
the Earth.
glenn
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for lots of creation/evolution information
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