Re: molten cores

On Mar 25, 5:29 pm, Chris L Peterson <c...@xxxxxxxxxxxxxxxxxx> wrote:
On Wed, 25 Mar 2009 10:10:58 -0400, "Seth Waterston"

<sethwaters...@xxxxxxxxx> wrote:
Radioactive decay from what elements and why wouldn't those element half
lives make them non-radioactive over billions of years?  Also, wouldn't the
radioactivity show up in magma reaching the surface?

The primary radioisotopes associated with internal heating are U-238
(4.47 billion year half-life), U-235 (704 million year), Th-232 (14.1
billion year), and K-40 (1.28 billion year). Given these long
half-lifes, there is plenty of remaining activity since the formation of
the material.

The estimated Earth-average bulk heating from radioactive decay in the
core, mantle, and crust is about 6e-12 watts/kg. That's a very small
amount of heat, but still plenty to account for the heating of the
Earth's core.

Although magma doesn't consist of core material at all, and only just
barely consists of mantle material, it is- like all the material making
up the Earth- radioactive. Again, the typical activity level is very
low, but that's all that is required in the case of the well insulated
core.
_________________________________________________

Chris L Peterson
Cloudbait Observatoryhttp://www.cloudbait.com


You can't explain the dynamics which cause the Earth to deviate from a
perfect sphere nor the same mechanism which generates the evolution of
the surface crust that less than perfectly spherical profile.

You can't put anything into proper context as that is the dominant
trait of a mathematician or an astrologer but a person looking at the
Mid Atlantic ridge ,its orientation and its features would recognise
rotational traits immediately -

http://upload.wikimedia.org/wikipedia/commons/7/76/Mid-atlantic_ridge.jpg

You may as well be discussing a flat Earth but then again,when you
believe in a rotating dome of stars as something valid.
.

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