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Canis Lupus
2017-Jan-13, 08:42 PM
Hi,

I was wondering if there has been any attempt to explain the mid-ocean rift system by reference to the Sun's gravity?

Have there been any models, for example, testing the effect on a similarly constructed (in miniature) spinning sphere subject to an attracting force of similar strength to the Sun?

I note the present mainstream explanation is plate tectonics, however, it is not inconceivable that the Sun's gravity is playing a part, perhaps at an increasing rate.

Swift
2017-Jan-13, 10:14 PM
<snip>
however, it is not inconceivable that the Sun's gravity is playing a part, perhaps at an increasing rate.
I can't conceive of any way the Sun's gravity could play a part, particularly at an increasing rate. Why would it be increasing - the sun and Earth aren't getting closer, nor are they changing significantly in mass?
Why would the sun's gravity have an effect on mid-ocean rifts (either their location, their rate of spreading, or whatever)?
I doubt tidal heating from the sun is significant, particularly compared to other sources (like radioactive decay).
What about mid ocean rifts is not explained by plate tectonics, and thus needs an alternative explanation?

Canis Lupus
2017-Jan-13, 10:35 PM
I can't conceive of any way the Sun's gravity could play a part, particularly at an increasing rate. Why would it be increasing - the sun and Earth aren't getting closer, nor are they changing significantly in mass?
Why would the sun's gravity have an effect on mid-ocean rifts (either their location, their rate of spreading, or whatever)?
I doubt tidal heating from the sun is significant, particularly compared to other sources (like radioactive decay).
What about mid ocean rifts is not explained by plate tectonics, and thus needs an alternative explanation?

It may have been better if I do not include the last paragraph of the OP.

Putting aside that last paragraph, which was only included to give my questions some context, I still seek any answer, if there is any, to my query.

To answer your questions might invoke ATM considerations. My intention is not to use Q & A to put forward an ATM, but rather eliminate to my own satisfaction alternative ideas which may seem to have sense but the literature has already eliminated or not not bothered to consider for good reason. If there is no good reason or it has not been eliminated, then I do not feel compelled to abandon the wonder of the idea immediately.

But, I will state this: I am aware that the idea of planetary migration is being discussed in mainstream science in light of what is perceived as atypical solar system configurations being discovered. If the idea has any validity, then one possible explanation is an increasing level of gravity applying to those solar systems. Then I suppose it is fair to wonder if one system experiences increased gravity causing this migration, why not ours? Following that idea, if it does occur, one might legitimately speculate that the effects of that increasing gravity will manifest gradually on the surface of a planet until it is eventually ripped apart from the increasing gravity. A rift in a planet might be the first sign of this process.

I only post the above to give a sample of the thinking behind the question, not to advocate a theory, but to wonder and explore an idea which may or may not have some validity in it.

Swift
2017-Jan-13, 10:50 PM
<snip>
But, I will state this: I am aware that the idea of planetary migration is being discussed in mainstream science in light of what is perceived as atypical solar system configurations being discovered. If the idea has any validity, then one possible explanation is an increasing level of gravity applying to those solar systems.
I have never heard of "increasing level of gravity" as an explanation of planetary migration and I don't even know what "increasing level of gravity" could possibly mean.

In a multiple body system, some configurations of objects (such as planets orbiting a star) are not stable, particularly over long periods of time, and thus the orbits of those planets may change. There is no need to evoke changing levels of gravity. And since there is no "changing levels of gravity" affecting orbits, there is certainly no effect on the surfaces of those planets.

Canis Lupus
2017-Jan-13, 10:58 PM
I have never heard of "increasing level of gravity" as an explanation of planetary migration and I don't even know what "increasing level of gravity" could possibly mean.

In a multiple body system, some configurations of objects (such as planets orbiting a star) are not stable, particularly over long periods of time, and thus the orbits of those planets may change. There is no need to evoke changing levels of gravity. And since there is no "changing levels of gravity" affecting orbits, there is certainly no effect on the surfaces of those planets.

How does this fit in with your contention that there is no changing levels of gravity as a statement of principle?

http://curious.astro.cornell.edu/physics/57-our-solar-system/planets-and-dwarf-planets/orbits/81-when-the-sun-converts-mass-to-energy-do-the-orbits-of-the-planets-change-advanced

Hornblower
2017-Jan-13, 11:02 PM
How does this fit in with your contention that there is no changing levels of gravity as a statement of principle?

http://curious.astro.cornell.edu/physics/57-our-solar-system/planets-and-dwarf-planets/orbits/81-when-the-sun-converts-mass-to-energy-do-the-orbits-of-the-planets-change-advanced

All that article says is that the Sun's mass, and thus its gravitational force, is decreasing. Nothing about an increase.

Canis Lupus
2017-Jan-13, 11:07 PM
All that article says is that the Sun's mass, and thus its gravitational force, is decreasing. Nothing about an increase.

Yes, I appreciate that. It is an odd citation for any idea that the Sun's gravity might be increasing. But as a starting point in acknowledging the principle of a change (evolution) it does the job.

Swift
2017-Jan-13, 11:45 PM
How does this fit in with your contention that there is no changing levels of gravity as a statement of principle?

http://curious.astro.cornell.edu/physics/57-our-solar-system/planets-and-dwarf-planets/orbits/81-when-the-sun-converts-mass-to-energy-do-the-orbits-of-the-planets-change-advanced
From the link (with my bolding)

Overall, I think it is safe to conclude that (a) there will be no noticeable effect on the planets' orbits over anything resembling a human lifetime, and (b) there will be a noticeable effect over timescales approaching the lifetime of the Sun, since the Sun will lose around 0.07% of its mass over that time period, leading to a change in the Earth's orbital period of about half a day.

So it will not be significant over the period time during which planetary migration may have taken place in the early solar system and it will have even a less significant effect on plate tectonics (in other words, no effect).

And, as Hornblower points out, it is a decreasing effect, not an increasing effect.

So I would say it is an irrelevant reference.

Canis Lupus
2017-Jan-13, 11:55 PM
From the link (with my bolding)


So it will not be significant over the period time during which planetary migration may have taken place in the early solar system and it will have even a less significant effect on plate tectonics (in other words, no effect).

And, as Hornblower points out, it is a decreasing effect, not an increasing effect.

So I would say it is an irrelevant reference.

Fair enough, although it is a different principle you are now asserting. Fine, that's part of the process of Q & A as far as I can tell.

Interesting to note, leaving aside whether it shows anything significant one way or another, the calculation does not take into consideration the effect on other planets, and their affect on the orbits of other planets in the system. I can't eliminate a compounding effect which once set off leads to significant changes from a whole lot of insignificant ones.

Hornblower
2017-Jan-14, 12:18 AM
Fair enough, although it is a different principle you are now asserting. Fine, that's part of the process of Q & A as far as I can tell.

Interesting to note, leaving aside whether it shows anything significant one way or another, the calculation does not take into consideration the effect on other planets, and their affect on the orbits of other planets in the system. I can't eliminate a compounding effect which once set off leads to significant changes from a whole lot of insignificant ones.

Maybe you or I can't eliminate it, but experts in planetary orbital dynamics can and do eliminate it. If I am not mistaken, the orbits of the planets have been in their current states, or very close to being so, for far longer than the current round of continental drift that has opened up the Atlantic Ocean. That started during the dinosaur era, long after the planetary orbits had stabilized. At least, that has been my understanding from multiple sources.

Canis Lupus
2017-Jan-14, 12:33 AM
Maybe you or I can't eliminate it, but experts in planetary orbital dynamics can and do eliminate it. If I am not mistaken, the orbits of the planets have been in their current states, or very close to being so, for far longer than the current round of continental drift that has opened up the Atlantic Ocean. That started during the dinosaur era, long after the planetary orbits had stabilized. At least, that has been my understanding from multiple sources.

Dose darn dinos did it den!:doh:

Canis Lupus
2017-Jan-14, 07:29 PM
Maybe you or I can't eliminate it, but experts in planetary orbital dynamics can and do eliminate it. If I am not mistaken, the orbits of the planets have been in their current states, or very close to being so, for far longer than the current round of continental drift that has opened up the Atlantic Ocean. That started during the dinosaur era, long after the planetary orbits had stabilized. At least, that has been my understanding from multiple sources.

I hope they did a better job than the expert I linked to. That's not meant as a criticism of him although I can see how it could be viewed like that. I understand he was dealing with a discrete issue, but he could have mentioned potential other factors without bothering with the details.

Hornblower
2017-Jan-14, 11:43 PM
I hope they did a better job than the expert I linked to. That's not meant as a criticism of him although I can see how it could be viewed like that. I understand he was dealing with a discrete issue, but he could have mentioned potential other factors without bothering with the details.
Potential other factors of what?

grapes
2017-Jan-14, 11:58 PM
I hope they did a better job than the expert I linked to. That's not meant as a criticism of him although I can see how it could be viewed like that. I understand he was dealing with a discrete issue, but he could have mentioned potential other factors without bothering with the details.
Are you familiar with all of the expanding earth hypotheses?

https://en.m.wikipedia.org/wiki/Expanding_Earth

Just because you are not familiar with all the possibilities, doesn't mean the "experts" aren't. Debunked theories do not need to be brought up every time.

Canis Lupus
2017-Jan-15, 12:16 AM
Are you familiar with all of the expanding earth hypotheses?

https://en.m.wikipedia.org/wiki/Expanding_Earth

Just because you are not familiar with all the possibilities, doesn't mean the "experts" aren't. Debunked theories do not need to be brought up every time.

I'm aware of the theory, but can't see how it relates.

Canis Lupus
2017-Jan-15, 12:21 AM
Potential other factors of what?

His basic purpose was to do a calculation to determine if the Sun's gravity would be altered due to mass change. He then concluded, from that calculation, that Earth's orbit would not alter in any significant way.

There are other factors which may cause Earth's orbit to alter apart from changes in the Sun's mass is my point. He could've mentioned them, but that was not the primary point of his work. Fair enough, he done more than enough free work.

grapes
2017-Jan-15, 12:21 AM
I'm aware of the theory, but can't see how it relates.
Your criticism of Ask an Astronomer. Expanding earth theories are alternate explanations of rift systems

Canis Lupus
2017-Jan-15, 01:21 AM
Your criticism of Ask an Astronomer. Expanding earth theories are alternate explanations of rift systems

Ok. but he wasn't dealing with rifts, but orbits. As such, it would be senseless to expect him to mention it at all. Besides, what I'm suggesting as a little addition to the well written article does not mean fringe theories, but mainstream ones.

grapes
2017-Jan-15, 01:30 AM
Ok. but he wasn't dealing with rifts, but orbits. As such, it would be senseless to expect him to mention it at all. Besides, what I'm suggesting as a little addition to the well written article does not mean fringe theories, but mainstream ones.That was my point. I wasn't suggesting that Ask an Astronmer add anything to their article. Some of the expanding earth theories involve increases in gravity.

Wait, are you saying they're all fringe theories?

Nowhere Man
2017-Jan-15, 02:54 AM
But, I will state this: I am aware that the idea of planetary migration is being discussed in mainstream science in light of what is perceived as atypical solar system configurations being discovered. If the idea has any validity, then one possible explanation is an increasing level of gravity applying to those solar systems. Then I suppose it is fair to wonder if one system experiences increased gravity causing this migration, why not ours? Following that idea, if it does occur, one might legitimately speculate that the effects of that increasing gravity will manifest gradually on the surface of a planet until it is eventually ripped apart from the increasing gravity. A rift in a planet might be the first sign of this process.

First off, there is nothing to the idea of "increasing level of gravity." Gravity is an effect of mass, and to get more gravity you have to add more mass. Nothing is adding any significant mass to the sun. True, the Sun is fusing hydrogen to helium, and the solar wind is carrying off particles, but again this amount is insignificant.

Planetary migration is caused by gravitational interactions between planets, and can send planets inward or outward.

Planets won't be stretched until they get near the Sun's Roche limit, and Earth is nowhere near that -- it's thousands of times further out. Plate tectonics adequately explains the observed rifts on Earth.

Fred

ToSeek
2017-Jan-17, 04:53 PM
This has clearly gone beyond the remit of the Q&A Forum, so I've moved it to the Geology Forum, with a redirect.

John Mendenhall
2017-Jan-17, 07:58 PM
First off, there is nothing to the idea of "increasing level of gravity." Gravity is an effect of mass, and to get more gravity you have to add more mass. Nothing is adding any significant mass to the sun. True, the Sun is fusing hydrogen to helium, and the solar wind is carrying off particles, but again this amount is insignificant.

Planetary migration is caused by gravitational interactions between planets, and can send planets inward or outward.

Planets won't be stretched until they get near the Sun's Roche limit, and Earth is nowhere near that -- it's thousands of times further out. Plate tectonics adequately explains the observed rifts on Earth.

Fred

Did you mean "further in"?

Canis Lupus
2017-Jan-21, 02:10 AM
I don't agree that this is primarily a geological issue, although I am happy for it to be here than anywhere else. Geology in the context of this discussion is data which is being interpreted. It is quite valid to interpret that data geologically, but it is just as valid to interpret it astronomically for a number of reasons. One is simply that Mars shows signs of a rift also. It is speculated that the rift on Mars has been caused by the immense volcanoes, however, I've never read anything sensible supporting that idea. That then leaves it open to wonder about the connection between rifts on Earth and Mars. Yes, one can do that with or without reference to larger astronomical forces at play, but it is still an astronomical issue because it involves astronomical comparisons.

I have no issue with the correlation of mass and gravity being accepted as a given, however, whether or not it is a direct causal relationship is open to legitimate scientific speculation.

grapes
2017-Jan-26, 12:38 AM
I don't agree that this is primarily a geological issue, although I am happy for it to be here than anywhere else. Geology in the context of this discussion is data which is being interpreted. It is quite valid to interpret that data geologically, but it is just as valid to interpret it astronomically for a number of reasons. One is simply that Mars shows signs of a rift also. It is speculated that the rift on Mars has been caused by the immense volcanoes, however, I've never read anything sensible supporting that idea.

The possible connections between volcanism and rifts appear in a lot of the literature--but also in the introductory textbooks. What part of that is not sensible?


That then leaves it open to wonder about the connection between rifts on Earth and Mars. Yes, one can do that with or without reference to larger astronomical forces at play, but it is still an astronomical issue because it involves astronomical comparisons.

Still, the title of the (sub)forum is "Geology and Planetary Surfaces", seems like it's a pretty good fit for "planetary surfaces"


I have no issue with the correlation of mass and gravity being accepted as a given, however, whether or not it is a direct causal relationship is open to legitimate scientific speculation.
Unfortunately, also, illegitimate. :)h

Reality Check
2017-Jan-26, 02:09 AM
I don't agree that this is primarily a geological issue, although I am happy for it to be here than anywhere else.
The formation of geological features such as the Mid Ocean Rift System (https://en.wikipedia.org/wiki/Mid-ocean_ridge) or Valles Marineris (https://en.wikipedia.org/wiki/Valles_Marineris) are primarily a geological issue.
It is invalid to interpret them astronomically when there is no valid astronomical mechanism to create them or speculate without evidence.

Canis Lupus
2017-Jan-31, 12:53 AM
The possible connections between volcanism and rifts appear in a lot of the literature--but also in the introductory textbooks. What part of that is not sensible?

The only explanation I've read is that the volcanoes on Mars stretch the surface of the planet making the rift. This is contrary to the basic principle of how volcanoes build themselves to a height on Earth. No data has been pointed to, which I am aware of, which suggests Mar's volcanoes built themselves up in any other way than the ones on Earth, putting aside plate tectonics explanation as to why Earth's volcanoes never reach anywhere near the height of Mars. Point is they build height the same way. How can that building process cause a rift like Mars' and where on Earth do we find similar examples of rifts caused by volcanoes? We may find some correlations, but overall even that is not there as a strong pattern of correlation. Please correct me if I am wrong.

Canis Lupus
2017-Jan-31, 12:56 AM
Unfortunately, also, illegitimate. :)h

Given the discussions throughout this board, I would have thought the statement so conservative as to be safe. You seem to be taking conclusions one step further.

Canis Lupus
2017-Jan-31, 01:02 AM
Planets won't be stretched until they get near the Sun's Roche limit, and Earth is nowhere near that -- it's thousands of times further out. Plate tectonics adequately explains the observed rifts on Earth.

Fred

I'd question this: does the idea of a "Roche limit" take into consideration duration of time - a long time. To make an analogy of time being a necessary ingredient interpretation is that our so called solid planet's surface acts more like a liquid over time. Likewise, I suspect, a Roche limit may be affected by time also. However, I am open to any suggestion that this time factor is included in the calculation of the Roche limit. One indicia of being included would be that the limit moves over time.

Reality Check
2017-Jan-31, 01:14 AM
Any body outside of the Roche limit (https://en.wikipedia.org/wiki/Roche_limit) will not disintegrate no matter how long it orbits, e.g. the Moon has not disintegrated in the last 4.6 billion years. This is irrelevant to a discussion of the formation of the Mid Ocean Rift System or Valles Marineris since the Earth and Mars are vastly outside of the Roche limit of the Sun. There is no significant stretching caused by the Sun and thus no geological consequences.

Canis Lupus
2017-Jan-31, 01:56 AM
Any body outside of the Roche limit (https://en.wikipedia.org/wiki/Roche_limit) will not disintegrate no matter how long it orbits, e.g. the Moon has not disintegrated in the last 4.6 billion years. This is irrelevant to a discussion of the formation of the Mid Ocean Rift System or Valles Marineris since the Earth and Mars are vastly outside of the Roche limit of the Sun. There is no significant stretching caused by the Sun and thus no geological consequences.

Sorry to persist but we aren't really discussing "disintegration". I know it's a simple point, but very relevant. An object can stress another object without destruction. I just look at my face in the mirror each morning to see this.

Reality Check
2017-Jan-31, 03:01 AM
I know we are not discussing disintegration but that is what the Roche limit is about and what makes it irrelevant to this thread. Likewise the unsupported idea that gravitation from other bodies such as the Sun is irrelevant to this thread.
The geology in Mid Ocean Rift System (https://en.wikipedia.org/wiki/Mid-ocean_ridge) and Valles Marineris (https://en.wikipedia.org/wiki/Valles_Marineris) are relevant to this thread.

Canis Lupus
2017-Jan-31, 09:31 PM
The possible connections between volcanism and rifts appear in a lot of the literature--but also in the introductory textbooks. What part of that is not sensible?

Although I have already replied to the above in another post, I had an additional thought last night about this issue.

The three large volcanoes on Mars are reasonably close together in the one hemisphere in the same direction away from the rift, not too far away from the rift. Yes, that might suggest a connection between the two - the rift and the volcanoes - however the rift itself shows no distortion towards the direction of the volcanoes. It is fairly symmetrical. If the volcanoes were stretching the "skin" of Mars to make the rift, you'd expect to observe a distortion towards the volcanoes. It is not present. I think in this case, Occam's Razor applies - the simple and well known explanation for volcano formation is the best one, one which does not result in the stretching of a planet's surface. Any explanation for the rift using "volcano stretch" appears to be a complicated unknown process, but I would welcome correction as always.

Canis Lupus
2017-Jan-31, 09:38 PM
I know we are not discussing disintegration but that is what the Roche limit is about and what makes it irrelevant to this thread. Likewise the unsupported idea that gravitation from other bodies such as the Sun is irrelevant to this thread.
The geology in Mid Ocean Rift System (https://en.wikipedia.org/wiki/Mid-ocean_ridge) and Valles Marineris (https://en.wikipedia.org/wiki/Valles_Marineris) are relevant to this thread.

Agreed. The idea in bold is best left alone in this thread.

Reality Check
2017-Jan-31, 09:57 PM
The three large volcanoes on Mars are reasonably close together in the one hemisphere in the same direction away from the rift, not too far away from the rift. Yes, that might suggest a connection between the two - the rift and the volcanoes -....
This is not quite what the proposed mechanism for Valles Marineris (https://en.wikipedia.org/wiki/Valles_Marineris) seems to be, It is not that the volcanoes cause the rift system. It is more that they have a common cause.

The formation of Valles Marineris is thought to be closely tied with the formation of the Tharsis Bulge. The Tharsis Bulge was formed from the Noachian to Late Hesperian period of Mars, in three stages. The first stage consisted of a combination of volcanism and isostatic uplift; soon, however, the volcanism loaded the crust to a point at which the crust could no longer support the added weight of Tharsis, leading to widespread graben formation in the elevated regions of Tharsis. Stage two consisted of more volcanism and a loss of isostatic equilibrium; the source regions of the volcanism no longer resided underneath Tharsis, creating a very large load. Finally, the crust failed to hold up Tharsis and radial fractures formed, including at Valles Marineris. Stage three mainly consisted of more volcanism and asteroid impacts. The crust, having already reached its failure point, just stayed in place and younger volcanoes formed. Tharsis volcanism involved very low viscosity magma, forming shield volcanoes similar to those of the Hawaiian Island chain, but, because there is minor or no current active plate tectonics on Mars, the hotspot activity led to very long histories of repeated volcanic eruptions at the same spots, creating some of the largest volcanoes in the solar system, including the biggest, Olympus Mons.[8]
Mars has no current tectonic movement. If a hot spot like the one under the Hawaiian Islands forms on Mars then it stays in one place. That allowed the formation of the Tharsis Bulge. Failures of the crust of the bulge formed rifts such as Valles Marineris.

I suppose an analogy would be baking bread - it starts as a smooth dough blob but as it expands it can form fissures, rifts and peaks.

Canis Lupus
2017-Jan-31, 10:25 PM
This is not quite what the proposed mechanism for Valles Marineris (https://en.wikipedia.org/wiki/Valles_Marineris) seems to be, It is not that the volcanoes cause the rift system. It is more that they have a common cause.

Mars has no current tectonic movement. If a hot spot like the one under the Hawaiian Islands forms on Mars then it stays in one place. That allowed the formation of the Tharsis Bulge. Failures of the crust of the bulge formed rifts such as Valles Marineris.

I suppose an analogy would be baking bread - it starts as a smooth dough blob but as it expands it can form fissures, rifts and peaks.

Thanks, that is a more thorough and fuller explanation than the one I had read about which had mentioned "stretching". Although I can't say using any reason one way or another if it seems correct to me, on the surface (so to speak) it appears to make more sense.

Canis Lupus
2017-Feb-01, 09:57 PM
The formation of Valles Marineris is thought to be closely tied with the formation of the Tharsis Bulge. The Tharsis Bulge was formed from the Noachian to Late Hesperian period of Mars, in three stages. The first stage consisted of a combination of volcanism and isostatic uplift; soon, however, the volcanism loaded the crust to a point at which the crust could no longer support the added weight of Tharsis, leading to widespread graben formation in the elevated regions of Tharsis. Stage two consisted of more volcanism and a loss of isostatic equilibrium; the source regions of the volcanism no longer resided underneath Tharsis, creating a very large load. Finally, the crust failed to hold up Tharsis and radial fractures formed, including at Valles Marineris. Stage three mainly consisted of more volcanism and asteroid impacts. The crust, having already reached its failure point, just stayed in place and younger volcanoes formed. Tharsis volcanism involved very low viscosity magma, forming shield volcanoes similar to those of the Hawaiian Island chain, but, because there is minor or no current active plate tectonics on Mars, the hotspot activity led to very long histories of repeated volcanic eruptions at the same spots, creating some of the largest volcanoes in the solar system, including the biggest, Olympus Mons.[8]

Two problems here:

1. The rift should be circular around the collapse. Not a line along an equator.
2. The rift still should show signs of distortion towards the collapsed area. If anything there are signs of distortion away in all the wrong places.

Reality Check
2017-Feb-01, 10:05 PM
Geologists are content with the proposed mechanism. As what you quoted states - Finally, the crust failed to hold up Tharsis and radial fractures formed, including at Valles Marineris.
Where did you get that idea of a collapse producing a circular rift?

Canis Lupus
2017-Feb-01, 10:13 PM
Geologists are content with the proposed mechanism. As what you quoted states - Finally, the crust failed to hold up Tharsis and radial fractures formed, including at Valles Marineris.
Where did you get that idea of a collapse producing a circular rift?

By looking at where one would expect the collapses to be greatest - around the largest volcanoes.

Canis Lupus
2017-Feb-01, 10:14 PM
... is thought to be closely tied ....

Any geologist content with the above needs to be reeducated. Apologies for the bluntness, but it's one thing for a geologist to think the above is best theory, it is a big step further to be content with it.

Reality Check
2017-Feb-01, 10:19 PM
By looking at where one would expect the collapses to be greatest - around the largest volcanoes.
Read what you quote again - those "largest volcanoes" formed after Valles Marineris!

Reality Check
2017-Feb-01, 10:28 PM
Any geologist content with the above needs to be reeducated.
Rather than insulting geologists you should learn the likely mechanism for the formation of Valles Marineris (https://en.wikipedia.org/wiki/Valles_Marineris#Formation)

"a combination of volcanism and isostatic uplift" creates the Tharsis bulge. The first "rifts" appear - grabens (https://en.wikipedia.org/wiki/Graben).
More volcanism causes a loss of isostasy (https://en.wikipedia.org/wiki/Isostasy), i.e. denser material on the surface is no longer buoyed up by subsurface rocks. Thus:
"Finally, the crust failed to hold up Tharsis and radial fractures formed, including at Valles Marineris."
More volcanism including the formation of the largest volcanoes in the Solar System.


ETA: Maybe the "bulge" term is confusing you. Tharsis is a volcanic plateau (https://en.wikipedia.org/wiki/Tharsis). It "bulges" above the surrounding terrain but is not a mound like a volcano. It is not even that circular - more of a peanut shape.

Canis Lupus
2017-Feb-01, 10:33 PM
Rather than insulting geologists you should learn geology ...

Please don't misinterpret my post in such a negative fashion.

For one thing, there are good geologists and ordinary ones, just like there are good lawyers and tradesman called craftsmen. To suggest that some of the part needs to adjust its thinking is no slur on the remainder of the whole. In fact, it is a tribute to their standard.

The quote doesn't actually state geologists are content. That was your assertion. I was being polite towards you in pointing away from you but towards geologists who need reform.

Don't worry about my level of geological understanding. Ever since I touched Susan's hand in the snowy mountains when we were the tender age of 16, it is has been of intense interest to me. It's funny what can inspire a person to take an almost life long interest in certain things. Sorry, but you have to appreciate that Susan had perfect wavy blonde hair, blue eyes, slim and most of all glaringly intelligent. Now chief surgeon at this country's finest children hospital.

Reality Check
2017-Feb-01, 10:40 PM
Please don't misinterpret my post in such a negative fashion.
A comment that geologists content with "most agreed upon theory today" need to be reeducated is negative in any interpretation. It is geologists who proposed and support the mechanism you quoted.
My main point was that you seem to not understand what you quoted so:
You should learn the likely mechanism for the formation of Valles Marineris (https://en.wikipedia.org/wiki/Valles_Marineris#Formation)

"a combination of volcanism and isostatic uplift" creates the Tharsis bulge. The first "rifts" appear - grabens (https://en.wikipedia.org/wiki/Graben).
More volcanism causes a loss of isostasy (https://en.wikipedia.org/wiki/Isostasy), i.e. denser material on the surface is no longer buoyed up by subsurface rocks. Thus:
"Finally, the crust failed to hold up Tharsis and radial fractures formed, including at Valles Marineris."
More volcanism including the formation of the largest volcanoes in the Solar System.

Maybe the "bulge" term is confusing you. Tharsis is a volcanic plateau (https://en.wikipedia.org/wiki/Tharsis). It "bulges" above the surrounding terrain but is not a mound like a volcano. It is not even that circular - more of a peanut shape.

Do you understand now that the big volcanos formed after Valles Marineris?

geonuc
2017-Feb-01, 11:03 PM
Ever since I touched Susan's hand in the snowy mountains when we were the tender age of 16, it is has been of intense interest to me. It's funny what can inspire a person to take an almost life long interest in certain things.

As it was for me (without the touching Susan bit). Have you considered getting a degree in geology? I did and it was not only eye-opening, but a great experience.

Canis Lupus
2017-Feb-01, 11:24 PM
A comment that geologists content with "most agreed upon theory today" need to be reeducated is negative in any interpretation.

Couldn't disagree more with the above assertion. Although I can see how an argument could be maintained in its favour. It is trumped by science's relentless curiosity to refine and better understand everything.




It is geologists who proposed and support the mechanism you quoted.

Nothing controversial here though! It is as you would expect, but it says little about much.


Do you understand now that the big volcanos formed after Valles Marineris?

Yes, I saw that the text suggested that, but considered carefully that it might not be stating as much as well. It is Wiki after all - very helpful yes, but ...

I am quite happy for it to be correct. If it is, then the volcanoes have no relevance on the original formation of the rift. The point of this discussion is otherwise. I never brought them up as being relevant for the cause of the rift. It was someone else.

Canis Lupus
2017-Feb-01, 11:27 PM
As it was for me (without the touching Susan bit). Have you considered getting a degree in geology? I did and it was not only eye-opening, but a great experience.

No, my preference would be for physics, but at 54 and with my lifestyle in remote areas, I regard academia as over for me.

Physics runs into everything and everything to me must dovetail.

BTW I only touched her hand, telling her how beautiful it was. I'm sure that heart felt tribute to the delicacy of her hand served as no discouragement to her long climb to one of this country's finest surgeons. Gee, if I was conceited, I'd think it might serve as an inspiration to her. Such thinking is fanciful.

Reality Check
2017-Feb-01, 11:27 PM
My interest in geology stemmed more from getting up close and personal with hills and mountains in my tramping (hiking) and skiing days. Plus living in NZ with fairly frequent earthquakes.

Reality Check
2017-Feb-01, 11:34 PM
Yes, I saw that the text suggested that, but considered carefully that it might not be stating as much as well.
The text is quite explicit - the volcanoes formed after Valles Marineris. Thus any suggestion that the volcanoes created Valles Marineris needs evidence that they existed before Valles Marineris.
I suspect that the relative dating is derived from impact craters, maybe fewer craters on the volcanoes than in the canyon.

Canis Lupus
2017-Feb-01, 11:34 PM
My interest in geology stemmed more from getting up close and personal with hills and mountains in my tramping (hiking) and skiing days. Plus living in NZ with fairly frequent earthquakes.

I think anyone who was watched the All Blacks play with mountains for men would be drawn to geology. I love the Blacks and I'm not even Kiwi - more than the Wallabies.

Canis Lupus
2017-Feb-01, 11:37 PM
The text is quite explicit - the volcanoes formed after Valles Marineris. Thus any suggestion that the volcanoes created Valles Marineris needs evidence that they existed before Valles Marineris.
I suspect that the relative dating is derived from impact craters, maybe fewer craters on the volcanoes than in the canyon.

Ok, we are in complete agreement. Probably also agree that it will be a long time before the Wallabies beat the All Blacks again.

Reality Check
2017-Feb-01, 11:42 PM
A nitpick - the first mention of volcanoes in this thread came from you: It is speculated that the rift on Mars has been caused by the immense volcanoes... (https://forum.cosmoquest.org/showthread.php?163636-Mid-Ocean-Rift-System&p=2387320#post2387320) but you obviously know the current theory correctly now.

Canis Lupus
2017-Feb-01, 11:45 PM
My interest in geology stemmed more from getting up close and personal with hills and mountains in my tramping (hiking) and skiing days. Plus living in NZ with fairly frequent earthquakes.

Did a fair bit of this, still do, along the great dividing range of Australia. We have decent mountains here too. They just aren't in your face all the time like NZ.

Canis Lupus
2017-Feb-01, 11:46 PM
A nitpick - the first mention of volcanoes in this thread came from you: It is speculated that the rift on Mars has been caused by the immense volcanoes... (https://forum.cosmoquest.org/showthread.php?163636-Mid-Ocean-Rift-System&p=2387320#post2387320) but you obviously know the current theory correctly now.

That is a nitpick :)

I brought it up to dismiss - the exact opposite as a cause. Ok?

This is the quote you are looking for


The possible connections between volcanism and rifts appear in a lot of the literature--but also in the introductory textbooks. What part of that is not sensible?

Reality Check
2017-Feb-02, 12:22 AM
This is the quote you are looking for
You stated: I never brought them up as being relevant for the cause of the rift. (https://forum.cosmoquest.org/showthread.php?163636-Mid-Ocean-Rift-System&p=2389080#post2389080)
You were the first to bring up volcanoes as relevant to the cause of the rift: It is speculated that the rift on Mars has been caused by the immense volcanoes, however, I've never read anything sensible supporting that idea. (https://forum.cosmoquest.org/showthread.php?163636-Mid-Ocean-Rift-System&p=2387320#post2387320)
grapes replied with a general comment about the possible connections between volcanism and rifts in the literature.
You go onto an explanation that is wrong (and uncited): The only explanation I've read is that the volcanoes on Mars stretch the surface of the planet making the rift (https://forum.cosmoquest.org/showthread.php?163636-Mid-Ocean-Rift-System&p=2388736#post2388736).

Canis Lupus
2017-Feb-02, 12:25 AM
You stated: I never brought them up as being relevant for the cause of the rift. (https://forum.cosmoquest.org/showthread.php?163636-Mid-Ocean-Rift-System&p=2389080#post2389080)
You were the first to bring up volcanoes as relevant to the cause of the rift: It is speculated that the rift on Mars has been caused by the immense volcanoes... (https://forum.cosmoquest.org/showthread.php?163636-Mid-Ocean-Rift-System&p=2387320#post2387320)
grapes replied with a general comment about the possible connections between volcanism and rifts in the literature.


Ok, the thread speaks for itself. I'm very happy to let it speak for itself. Intelligent people will see for themselves what the thread says. I will not engage in discussion on this point any further