Re: Article: A Cool Early Earth?


Jo Schaper wrote:
> J. Taylor wrote:
> > Scientific American.com
> > September 26, 2005
> > A Cool Early Earth?
> >
> >
> > FULL ARTICLE:
> > http://www.sciam.com/print_version.cfm?articleID=0005FA5D-5F7C-1333-9F7C83414B7F0000
> >
> > EXCERPT:
> >
> > The textbook view that the earth spent its first half a billion years
> > drenched in magma could be wrong. The surface may have cooled
> > quickly--with oceans, nascent continents and the opportunity for life
> > to form much earlier
>
> Define "Cool". I'm skeptical.
>
Probably 374 C, water's critical temperature, above which water can no
longer be liquified no matter how deep the ocean. Zircons
(zirconium silicates), like the rest of the silicates, are not
presolar.
Therefore, they had to originate in deep oceans, where most silicates
(basalts) are formed. John Curtis

.