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Yes, Mage, radioactive decay (OT)
Posted By: SiliconDream <querl@uclink4.berkeley.edu>	Date: 11/13/99 11:10 p.m.
In Response To: Re: Inner and Outer cores. (Mage) Taken from the VolcanoWorld website (volcano.und.nodak.edu/vw.html): Dear Scott, Chuck, or Steve: I am in the fourth grade. We are studying the earth, the core, and volcanos. My question is How did the core get hot in the first place? Thank you. Billy Lacey Hi Billy, That is a good question. The story is, of course, kind of speculative, but it goes something like this: The Earth was a young planet just after the solar system formed, and it was consolidating out of the solar system nebula of dust and gas. As the young Earth contracted it started to get denser and denser and as the pressure went up the temperature went up too (just as when you pump air into your bicycle tire the temperature of the pump goes up). Additionally, there were still lots of other things flying around the solar system and many of them came crashing into the Earth as meteorites. All this also increased the temperature. Finally, there were a whole bunch of short-lived radioactive isotopes that were incorporated into the young Earth from the solar-system nebula. As you know, as elements decay radioactively they give off heat. These three processes combined to make the whole earth pretty hot. The story isn't over yet, though. Soon the Earth was hot enough to start melting, and when this happened the dense things (such as iron) could sink to the middle of the planet while the less dense things (such as silicates) could float to the surface. This is why we now have a layered Earth today. As all that iron "fell" to the center of the earth, it gave off a whole bunch of energy, and this event (called the iron catastrophe) generated a whole lot of heat as well. The Earth hasn't just been cooling off ever since, though. Although the short-lived radioactive isotopes were mostly used up way back before the iron catastrophe, the long-lived ones are still around. They are what keeps the interior hot today, and ultimately are the source of magmas/lavas at volcanoes. I hope this makes sense. Sincerely, Scott Rowland No, this isn't the only place I've seen this ; I've read it in some quite respectable textbooks. I was just too lazy to find and quote from any of them. :) It's a relatively modern theory (only came into vogue in the last 5-10 years), so the textbooks you've read may have been published too long ago. --SiliconDream

Message Index

Smoke plume and different sky revealed!	Wirehead	11/10/99 4:11 a.m.
Re: Smoke plume and different sky revealed!	MacDrugal	11/10/99 9:41 a.m.
Re: Smoke plume and different sky revealed!	wondercrank	11/10/99 2:22 p.m.
volcano if you ask me...	Ben Schodek	11/10/99 6:23 p.m.
Re: volcano if you ask me...	Mark Levin	11/10/99 7:07 p.m.
My kingdom for a ship.....:)	Sempiternity	11/11/99 10:13 a.m.
Re: volcano if you ask me...	SiliconDream	11/10/99 7:42 p.m.
Re: volcano if you ask me...	Mage	11/10/99 11:10 p.m.
Re: volcano if you ask me...	SiliconDream	11/11/99 12:10 a.m.
Re: volcano if you ask me...	Mage	11/11/99 5:49 p.m.
Inner and Outer cores.	Bachus	11/12/99 2:39 p.m.
Re: Inner and Outer cores.	Mage	11/12/99 3:36 p.m.
Re: Inner and Outer cores.	Desio	11/12/99 4:21 p.m.
Re: Inner and Outer cores.	Mage	11/13/99 12:30 p.m.
Yes, Mage, radioactive decay (OT)	SiliconDream	11/13/99 11:10 p.m.
Re: Yes, Mage, radioactive decay (OT)	Mage	11/14/99 1:01 a.m.
Re: Yes, Mage, radioactive decay (OT)	Mark Levin	11/14/99 1:23 a.m.
Switching focus.....	Sempiternity	11/14/99 12:40 p.m.
Powers up the Trademarked Weapon™	SiliconDream	11/14/99 3:37 a.m.
Re: Powers up the Trademarked Weapon™	Mage	11/14/99 10:41 a.m.
Re: Powers up the Trademarked Weapon™	SiliconDream	11/14/99 2:20 p.m.
Re: Powers up the Trademarked Weapon™	Mage	11/14/99 8:15 p.m.
Re: Powers up the Ultimate Weapon™	Mark Levin	11/14/99 9:50 p.m.
Really Boring Post	SiliconDream	11/15/99 1:21 a.m.
Re: volcano if you ask me...	Mage	11/10/99 11:16 p.m.
Re: volcano if you ask me...	MacDrugal	11/11/99 2:14 a.m.
Re: volcano if you ask me...	Louis Wu	11/11/99 9:12 p.m.
Re: volcano if you ask me...	MacDrugal	11/12/99 1:11 a.m.