<p>It is still a little known fact that radiation play an important role in the Earth's mantle. Experiments show that mantle-material becomes transparent to infrared radiation at increasing pressures (<a href="http://www.esrf.eu/news/general-old/general-2004/earthbadro/index_html">http://www.esrf.eu/news/general-old/general-2004/earthbadro/index_html</a>).</p>

<p>I would also say that the mantle is currently not understood in a way where estimates of heat-conduction-type versus depth can be accurately made. The heterogeneity of heat transfer (Cold detached subduction-slabs sinking to various depths and hot plumes quickly rising from the D''-layer) makes the question even more difficult.</p>

CC BY-SA 3.0
2014-04-17T11:27:50.637Z
2014-04-17T11:27:50.637Z
tobias47n9e
<p>Conduction probably is the main method in the crust, but do not underestimate fluid convection.</p>

<p>Every time you find a hot spring, then that is an example of fluid convection. Even volcanic eruptions could be considered convection.</p>

<p>Possibly even larger than these too, there is vigorous convection of seawater through young ocean crust. This can be seen on <a href="http://www.auscope.org.au/userfiles/file/Communications/Muller_etal_age_rate_asym_G3_2008-1.pdf" rel="nofollow">Figure 10 of Muller eta al Digital Models of the World's Ocean Crust</a>.  This plots depth vs age of ocean curve.  The "TBL" line approximates the curve that is expected for conductive cooling of the Earth's crust. Reality (the bars) are rather different. Although most of this cooling is in young rock, the accumulative effect shows in the older crust. (this plot is trying to demonstrate something else, but I couldn't find a good example of this classic graph that implied this convection must exist long before Black Smokers were ever discovered)</p>

CC BY-SA 3.0
2014-04-24T03:24:20.610Z
related: http://earthscience.stackexchange.com/questions/453
naught101
CC BY-SA 3.0
2014-04-17T12:29:19.510Z
Thanks for the answer, but I'm talking about heat getting up to the crust, not through it.
naught101
CC BY-SA 3.0
2014-04-17T22:48:42.920Z
(I probably shouldn't have mentioned it in the question - it's tangential, but thanks for addressing that comment).
naught101
CC BY-SA 3.0
2014-04-18T02:47:55.753Z
i'm skeptical convection or conduction has much to do with the crust; the bottom of the lithosphere acts as a strong insulator.
Neo
CC BY-SA 3.0
2014-04-17T12:22:44.160Z
2014-04-17T12:22:44.160Z
winwaed
<p>At wikipedia you can find some answers. <a href="http://en.wikipedia.org/wiki/Geothermal_gradient" rel="nofollow">http://en.wikipedia.org/wiki/Geothermal_gradient</a></p>

<p>Here it states that in the crust indeed conduction is the main method of heat trasfer. From the geothermal gradient it is also obvious that the outer core/mantle boundary is a big insulater. Since these two are separate heat transfer from the outer core to the mantle is also mainly by conduction.</p>

<p>For the mantle it is a story of both convection and conduction. I dont think the final answer is known here.</p>

<p>As an extra note. It seems that in your question you suggest that heat is generated in the core only. This is not true. Heat is also generated in the mantle through radioactive decay. This is estimated according to the linked wiki to be between 45 and 90% of the heat that escapes earth.</p>

CC BY-SA 3.0
2015-06-12T07:04:25.323Z
2015-06-12T07:04:25.323Z
user180146
<p>So, there are three main methods of transferring heat: radiation, convection/mass transfer, and conduction. Presumably radiation is not a major method of heat transport between the core and the crust, because it requires transparent materials (or a vacuum), and I don't think there is much of either in the mantle. Presumably conduction is the only significant method of transport in the crust, apart from volcanos.</p>

<p>So, in the mantle, between the core, where heat is generated, and the crust, where it is eventually dissapated, what proportion of heat is transported via convection and conduction?</p>

CC BY-SA 3.0
2014-04-23T06:06:10.427Z
@naught101, I don't understand what part of your question can't be answered straight from wikipedia. "Earth's internal heat flow to the surface is thought to be 80% due to mantle convection" http://en.wikipedia.org/wiki/Earth's_internal_heat_budget
Kenshin
CC BY-SA 3.0
2014-04-23T07:07:30.783Z
@Geodude: thanks for the link to that article. I hadn't seen it before. You're correct that it answers the entire question. Feel free to close this question.
naught101
CC BY-SA 3.0
2014-04-23T07:26:28.183Z
For reference: http://earthscience.stackexchange.com/questions/446/why-do-snowflakes-form-into-hexagonal-structures
naught101
CC BY-SA 3.0
2014-04-23T13:04:25.773Z
This question is not off-topic.
gerrit
CC BY-SA 3.0
2014-04-17T19:14:41.677Z
One of the reasons I have not weighed in on this question is its unclear if the question is talking about the "crust" which is very little, and the Lithosphere, which would be more significant. Also, mathjax would be very important to me answering this question, as it can be numerically approximated by looking a the Heat Equation, better known as the Diffusion Equation. Melting in the upper mantle plays a significant role in this question as well. This is a very complex question either way.
Neo
CC BY-SA 3.0
2014-04-17T22:47:03.547Z
@Neo: I'd be happy with an answer that just discussed heat flow from core to lithosphere. Your choice.
naught101
<geothermal-heat><mantle>
How is heat transferred from the core through the mantle to the crust?
naught101
# How is heat transferred from the core through the mantle to the crust?

(Asked by: username_0 on 2014-04-17)

So, there are three main methods of transferring heat: radiation, convection/mass transfer, and conduction. Presumably radiation is not a major method of heat transport between the core and the crust, because it requires transparent materials (or a vacuum), and I don't think there is much of either in the mantle. Presumably conduction is the only significant method of transport in the crust, apart from volcanos.

So, in the mantle, between the core, where heat is generated, and the crust, where it is eventually dissapated, what proportion of heat is transported via convection and conduction?

**Tags:** geothermal-heat, mantle

> **Comments:**
> **username_3**: One of the reasons I have not weighed in on this question is its unclear if the question is talking about the "crust" which is very little, and the Lithosphere, which would be more significant. Also, mathjax would be very important to me answering this question, as it can be numerically approximated by looking a the Heat Equation, better known as the Diffusion Equation. Melting in the upper mantle plays a significant role in this question as well. This is a very complex question either way.  
> **username_0**: @username_3: I'd be happy with an answer that just discussed heat flow from core to lithosphere. Your choice.  
> **username_1**: @username_0, I don't understand what part of your question can't be answered straight from wikipedia. "Earth's internal heat flow to the surface is thought to be 80% due to mantle convection" http://en.wikipedia.org/wiki/Earth's_internal_heat_budget  
> **username_0**: @Geodude: thanks for the link to that article. I hadn't seen it before. You're correct that it answers the entire question. Feel free to close this question.  
> **username_0**: For reference: http://earthscience.stackexchange.com/questions/446/why-do-snowflakes-form-into-hexagonal-structures  
> **username_2**: This question is not off-topic.  

---

## 3 answers

### Answer by username_4 on 2014-04-17. Score: 11

It is still a little known fact that radiation play an important role in the Earth's mantle. Experiments show that mantle-material becomes transparent to infrared radiation at increasing pressures (<http://www.esrf.eu/news/general-old/general-2004/earthbadro/index_html>).

I would also say that the mantle is currently not understood in a way where estimates of heat-conduction-type versus depth can be accurately made. The heterogeneity of heat transfer (Cold detached subduction-slabs sinking to various depths and hot plumes quickly rising from the D''-layer) makes the question even more difficult.


---

### Answer by username_5 on 2014-04-17. Score: 3

Conduction probably is the main method in the crust, but do not underestimate fluid convection.

Every time you find a hot spring, then that is an example of fluid convection. Even volcanic eruptions could be considered convection.

Possibly even larger than these too, there is vigorous convection of seawater through young ocean crust. This can be seen on [Figure 10 of Muller eta al Digital Models of the World's Ocean Crust](http://www.auscope.org.au/userfiles/file/Communications/Muller_etal_age_rate_asym_G3_2008-1.pdf). This plots depth vs age of ocean curve. The "TBL" line approximates the curve that is expected for conductive cooling of the Earth's crust. Reality (the bars) are rather different. Although most of this cooling is in young rock, the accumulative effect shows in the older crust. (this plot is trying to demonstrate something else, but I couldn't find a good example of this classic graph that implied this convection must exist long before Black Smokers were ever discovered)

> **Comments:**
> **username_0**: Thanks for the answer, but I'm talking about heat getting up to the crust, not through it.  
> **username_0**: (I probably shouldn't have mentioned it in the question - it's tangential, but thanks for addressing that comment).  
> **username_3**: i'm skeptical convection or conduction has much to do with the crust; the bottom of the lithosphere acts as a strong insulator.  
> **username_0**: related: http://earthscience.stackexchange.com/questions/453  

---

### Answer by username_6 on 2015-06-12. Score: 1

At wikipedia you can find some answers. <http://en.wikipedia.org/wiki/Geothermal_gradient>

Here it states that in the crust indeed conduction is the main method of heat trasfer. From the geothermal gradient it is also obvious that the outer core/mantle boundary is a big insulater. Since these two are separate heat transfer from the outer core to the mantle is also mainly by conduction.

For the mantle it is a story of both convection and conduction. I dont think the final answer is known here.

As an extra note. It seems that in your question you suggest that heat is generated in the core only. This is not true. Heat is also generated in the mantle through radioactive decay. This is estimated according to the linked wiki to be between 45 and 90% of the heat that escapes earth.


---

