Re: Early Earth likely had continents, was habitable, according to new study

In article <%0cff.580693$xm3.507991@attbi_s21>, george@xxxxxxxxxxxxxxxxxxxxx
(George) wrote:

> http://www.eurekalert.org/pub_releases/2005-11/uoca-eel111605.php
>
> A surprising new study by an international team of researchers has
> concluded Earth's continents most likely were in place soon after the
> planet was formed, overturning a long-held theory that the early planet was
> either moon-like or dominated by oceans.
> The team came to the conclusion following an analysis of a rare metal
> element known as hafnium in ancient minerals from the Jack Hills in Western
> Australia, thought to be among the oldest rocks on Earth. Hafnium is found
> in association with zircon crystals in the Jack Hills rocks, which date to
> almost 4.4 billion years ago.
>
> "These results support the view that the continental crust had formed by
> 4.4-4.5 billion years ago and was rapidly recycled into the mantle," the
> researchers wrote in Science Express. Led by Professor Mark Harrison of the
> Australian National University, the team also included University of
> Colorado Assistant Professor Stephen Mojzsis and researchers from the
> University of California, Los Angeles and Ecole Normale Superieure
> University in France.
>
> The researchers used hafnium as a "tracer" element, using isotopes to infer
> the existence of early continental formation on Earth dating to Hadeon Eon,
> which took place during the first 500 million years of Earth's history,
> said Mojzsis, an assistant professor of geological sciences at CU-Boulder.
> Mojzsis also is a member of CU-Boulder's Center for Astrobiology.
>
> "The evidence indicates that there was substantial continental crust on
> Earth within its first 100 million years of existence," said Mojzsis. "It
> looks like the Earth started off with a bang."

Hey, I could throw in that we all started with our parents....err.
Perhaps I shouldn't say that though. There might be right wing Christians like
Pat Robertson reading.

>
> A 2001 study led by Mojzsis published in the journal Nature showed evidence
> for the presence of water on Earth's surface roughly 4.3 billion years ago.
> "The view we are taking now is that Earth's crust, oceans and atmosphere
> were in place very early on, and that a habitable planet was established
> rapidly," said Mojzsis.


Firebird

Never trust anybody who is too sophisticated to own a rubber chicken.

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