New evidence on lightning strikes: Mountains a lot less stable than we think

Oct 15, 2013 by Kanina Foss

(Phys.org) —Lightning strikes causing rocks to explode have for the first time been shown to play a huge role in shaping mountain landscapes in southern Africa, debunking previous assumptions that angular rock formations were necessarily caused by cold temperatures, and proving that mountains are a lot less stable than we think.

In a world where are crucial to and water supply, this has vast implications, especially in the context of climate change.

Professors Jasper Knight and Stefan Grab from the School of Geography, Archaeology and Environmental Studies at Wits University used a to prove – for the first time ever – that lightning is responsible for some of the angular in the Drakensburg.

"A compass needle always points to magnetic north. But when you pass a compass over a land's surface, if the minerals in the rock have a strong enough , the compass will read the magnetic field of the rock, which corresponds to when it was formed. In the Drakensburg, there are a lot of basalt rocks which contain a lot of magnetic minerals, so they've got a very strong magnetic signal," says Knight.

If you pass a compass over an area where a lightning strike occurred, the needle will suddenly swing through 360 degrees.

"The energy of the lightning hitting the land's surface can, for a short time, partially melt the rock and when the rock cools down again, it takes on the magnetic imprint of today's magnetic field, not the magnetic field of millions of years ago when the rock was originally formed," says Knight.

Because of the movement of continents, magnetic north for the newly formed rock will be different from that of the older rock around it. "You have two superimposed geomagnetic signatures. It's a very useful indicator for identifying the precise location of where the lightning struck."

Knight and Grab mapped out the distribution of in the Drakensburg and discovered that lightning significantly controls the evolution of the mountain landscapes because it helps to shape the summit areas – the highest areas – with this blasting effect.

Previously, angular debris was assumed to have been created by changes typical of cold, periglacial environments, such as fracturing due to frost. Water enters cracks in rocks and when it freezes, it expands, causing the rocks to split apart.

Knight and Grab are challenging centuries old assumptions about what causes mountains to change shape. "Many people have considered mountains to be pretty passive agents, just sitting there to be affected by cold climates over these long periods of time.

"This evidence suggests that that is completely wrong. African mountain landscapes sometimes evolve very quickly and very dramatically over short periods of time. These are actually very sensitive environments and we need to know more about them."

It is also useful to try and quantify how much debris is moved by these blasts which can cause boulders weighing several tonnes to move tens of metres.

"We can identify where the angular, broken up material has come from, trace it back to source, and determine the direction and extent to which the debris has been blasted on either side. Of course we know from the South African Weather Service how many strikes hit the land's surface, so we can estimate how much volume is moved per square kilometre per year on average," says Knight.

The stability of the land's surface has important implications for the people living in the valleys below the mountain. "If we have lots of debris being generated it's going to flow down slope and this is associated with hazards such as landslides," said Knight.

Mountains are also inextricably linked to food security and water supply. In Lesotho, a country crucial to South Africa's water supply, food shortages are leading to overgrazing, exposing the surface and making mountain landscapes even more vulnerable to weathering by and other processes.

Knight hopes that this new research will help to put in place monitoring and mitigation to try and counteract some of the effects. "The more we increase our understanding, the more we are able to do something about it."

A research paper to be published in the scientific journal, Geomorphology, is available here.

Explore further: Predicting when lightning will strike

More information: Jasper Knight, Stefan W. Grab, Lightning as a geomorphic agent on mountain summits: Evidence from southern Africa, Geomorphology, dx.doi.org/10.1016/j.geomorph.2013.07.029, www.sciencedirect.com/science/… ii/S0169555X13003929

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User comments : 22

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Shelgeyr
1.4 / 5 (18) Oct 15, 2013
I'm thrilled that scientists are beginning to face the implications of the evidence of electrical scarring on Earth. This is hardly "the first time ever", unless they're talking specifically about "some of the angular rock formations in the Drakensburg", which given that paragraph's wording might indeed be the case.

See some discussions on these lines here:
Possible electrical scars on Planet Earth...
http://thunderbol...mp;t=363

Are Mountains the Result of a Duning Process?
http://thunderbol...p;t=2780

Help Us Explain Crater Formation!
http://thunderbol...p;t=4056
cantdrive85
1.5 / 5 (17) Oct 15, 2013
Electric discharge on a larger scale may explain "magnetic anomalies" found on the moon.
http://phys.org/n...oid.html
cantdrive85
1 / 5 (15) Oct 15, 2013
Not even theoretically - these anomalies are very large and no source of such a discharge is known.

You're right if you believe in waving bunnies, but remarkably in direct contrast to your statement electric discharge on much, much larger scales than this type of event occurs on the Sun daily. Also, it's readily acknowledged the moon was captured by Earth. In such a capture event two differently charged bodies will experience tremendous electric discharge between them as they approach one another, just as you experience electric discharge when you reach for a doorknob.
Shelgeyr
1.3 / 5 (16) Oct 15, 2013
Electric discharge on a larger scale may explain "magnetic anomalies" found on the moon
Not even theoretically - these anomalies are very large and no source of such a discharge is known.

You are incorrect as to the theories involved. There are indeed such theories - and I don't simply mean "hypotheses" - I mean theories backed up with laboratory evidence and known scaling parameters. Given what we know about the conductivity of plasmas, the voltage gradient of the Heliospheric Current Sheet (and its variability), it is easy and not unreasonable to posit numerous discharge scenarios between the sun and planetary bodies, between planets and other denizens of the solar system, between planets and moons (as is ongoing with Jupiter), and between solar objects and interlopers. There is no lack of candidate discharge sources. Your "not even theoretically" bespeaks a lack of knowledge, or a dogmatic refusal to examine the data, or both.
cantdrive85
1 / 5 (14) Oct 15, 2013
What facts have you presented? Just claims of "nuh-uh".

the solar plasma is way too conductive for to allow such a discharges.

The sun itself is an electric discharge, it is your skewed theoretical understanding of plasma which blinds you from seeing the obvious.

"The main observational evidence indicating the existence of cosmic electrical discharges is the same as that which would lead an external observer to conclude that lightning flashes occur in our own atmosphere — namely, the sudden change they effect in the spectra of the Sun, stars and galaxies. In the Sun's spectrum, lines suddenly appear indicating the existence of gas temperatures of hundreds of thousands or even millions of degrees."
C.E.R. Bruce Electric Fields in Space, Penguin Science Survey 1968, p. 173.

C.E.R. Bruce wrote many papers on the electrical discharge of stars, here's a snippet;
http://www.catast...s/bruce/
Mr_Science
2 / 5 (12) Oct 15, 2013
Even the trolls are arguing against the trolls now. What has this site come to?

Back to the topic of the article - Lighting eroding mountains is an interesting concept. However, I doubt it's a big portion of the erosion that happens. Water is the key player when it comes to erosion with wind being a close second. I find it fascinating we now understand the processes so well that we can start to look for the smaller contributors.
cantdrive85
1 / 5 (15) Oct 15, 2013
Come on - the Sun is not an electric discharge, it's a ball of hydrogen plasma.


And phenomena that occur in plasma are electrical in nature, this is the disconnect between the EU/PC and most other theories. Over a hundred years of research of electric discharge in plasma has shown this to be true beyond the shadow of a doubt, it's the theoreticians who can't seem to grasp this notion. This is the exact notion Alfven was so critical of, the fact that years of lab research is ignored in favor of theoretical beliefs such as yours.
HannesAlfven
1.3 / 5 (14) Oct 15, 2013
Re: "Even the trolls are arguing against the trolls now. What has this site come to?"

So, now everybody who disagrees with ideology in science is now a "troll". What has science come to -- and more importantly -- where will it go now that people routinely confuse science as having only enough room for just one worldview ... ?

It's concerning that I need to say this, but astrophysics and cosmology are incredibly empirically challenged. If you are looking to modern-day cosmology for a worldview, then you might want to re-evaluate your approach to science, for you are enshrining two of the most speculative domains at the very base of your belief in science. This is an incredibly risky strategy ...
cantdrive85
1 / 5 (14) Oct 15, 2013
I find it fascinating we now understand the processes so well that we can start to look for the smaller contributors.

This innocuous statement is so anti-science it flies in the face of your claim to being Mr Science. Rube!
cantdrive85
1 / 5 (15) Oct 15, 2013
Well, the moon has been shown to have an atmosphere, however tenuous.
http://www.lpi.us...ts/lace/

The charge differential between the two bodies would be the driving factor. Ralph Juergens explains it well here;
http://saturnianc...gens.htm
Mr_Science
2 / 5 (12) Oct 15, 2013
@HannesAlfven
Incorrect, there is no ideology in science. If you disagree with proven theories then you must be able to show convincing evidence of such. However, you and the other trolls here have not shown any evidence for your claims. Therefore, it is trolling, not science.
BTW, there is only room for one world view because only one is correct. All other views either have been or will be proven incorrect.

@cantdrive85
Incorrect, there are no factual errors, claims of conspiracy, logical fallacies, or anything else that would be "anti-science" about my comment. However, I see all the above in most (if not all) of your comments.

Since neither of you have anything to say in relation to the article. I bid you happy trolling until your accounts have been deleted due to failure to follow the Comments guidelines.
cantdrive85
1 / 5 (14) Oct 15, 2013
They're not opened to any arguments which would contradict their scheme of thinking.

I have yet to see any incontrovertible evidence that shows phenomena in plasma to be anything but electrical discharge. Lots of claims are made, none seem forthcoming though.
HannesAlfven
1 / 5 (13) Oct 15, 2013
Re: "Incorrect, there is no ideology in science."

The physics community has already gone through this, and the American Institute of Physics actually stood down when Jeff Schmidt challenged them with his book, Disciplined Minds. You might want to go to Amazon.com and look that book up, because 700+ researchers were willing to put their careers on the line with their signatures, and Noam Chomsky joined in ...

Re: "If you disagree with proven theories then you must be able to show convincing evidence of such."

You also seem to not be aware that all theories are provisional. I know that philosophy is not in vogue right now, but it has not actually gone anywhere. And we relied upon it to get to this point, to begin with, so it's very short-sighted to just throw it all away.

You might also look into the philosophical problem of "unconceived alternatives" ...
HannesAlfven
1 / 5 (13) Oct 15, 2013
Re: "However, you and the other trolls here have not shown any evidence for your claims. Therefore, it is trolling, not science. BTW, there is only room for one world view because only one is correct. All other views either have been or will be proven incorrect."

You're espousing an epistemology which is alternatively labeled either positivism or scientism. A couple of disciplines of science have toyed around with this idea already, and have already moved on. It seems that the discipline of physics is now having its hand at this, with little reason suggested that they will be any more successful with it.

If you teach the ideology as part of the curriculum, purge the grad programs of those students who challenge those ideologies, and then fail to mention the problems & challenges with the ideology within the textbooks, then you've created a society of people who are simply ignorant of alternatives.

If you want to call that "science", then you've actually changed the definition ...
HannesAlfven
1 / 5 (13) Oct 15, 2013
Re: "But the proponents of Plasma universe are ideologists as well. They're not opened to any arguments which would contradict their scheme of thinking."

I've posted on the problem of the magnetohydrodynamics models to probably 20 or 30 articles on physorg over just the past two years or so. I've never once received any engagement on the issue. This is a huge red flag, because the models are widely known to not apply to collisionless plasmas -- and this problem has been known for more than four decades now. In fact, Alfven never meant for those idealized models to be used in this manner. He proposed that analysis as basically a thought experiment within a paper, and then the astrophysical community starting treating the idealization as though it's real.

The facts here are actually really simple to understand. The problem is that there is no desire or interest in learning about the history that led to these cosmic plasma models amongst textbook worshippers.
HannesAlfven
1 / 5 (13) Oct 15, 2013
Re: "I have yet to see any incontrovertible evidence that shows phenomena in plasma to be anything but electrical discharge."

Socrates would have asked these people to define what a plasma is. If you want to call it a plasma, but then choose to model it as a gas, then this is not "science". It's silly word games. Many people have apparently stopped thinking about what it is that they are "learning". And in fact, this is really part of the problem today -- because those grad students who do stop to think about these big questions tend to fall behind in the programs ... suggesting rather plainly that the graduate programs have become too much like a memorization competition.

Science is more than just brain tricks. Not only do have to learn how to work with these huge disciplines of knowledge; we also absolutely have to learn how to question the knowledge structures too. It's called critical thinking, guys ...
Mr_Science
1.8 / 5 (10) Oct 15, 2013
You're espousing an epistemology which is alternatively labeled either positivism or scientism. A couple of disciplines of science have toyed around with this idea already, and have already moved on. It seems that the discipline of physics is now having its hand at this, with little reason suggested that they will be any more successful with it.

I am stating a fact. The universe can only work one way.
If you want to call that "science", then you've actually changed the definition

All of science is based on the fact there is only one way the universe works and is understandable by human beings. Someone that does not agree with this is not doing science.
HannesAlfven
1 / 5 (12) Oct 15, 2013
Re: "I am stating a fact. The universe can only work one way."

But, you seem to be implying that you definitively know what this one way is ... And yet, this "truth" you speak of has thus far failed to account for more than 4% of the universe. Perhaps you should suggest that you know at least 4% of the truth, because in most disciplines, knowing 4% of something is taken to mean that you don't understand the system at all.

In science education reform circles, the constructivist epistemology is emerging as the epistemology of choice, in sharp contrast with positivism. That's because teaching people that they have a lock on "the truth" closes their minds to alternatives -- which interferes with the cultivation of critical thinking. Constructivism seeks to perfect the process of dialogue by encouraging and facilitating the clash of worldviews. Rather than telling students *what* to think, it helps them to understand *how* to think better.
Mr_Science
2.1 / 5 (11) Oct 15, 2013
But, you seem to be implying that you definitively know what this one way is

You are verifiably mistaken, all I have stated is if you disagree with the currently held theories you must provide convincing evidence. Otherwise you have no scientific standing. Please read my post before bothering to reply.
HannesAlfven
1 / 5 (12) Oct 15, 2013
Re: "You are verifiably mistaken, all I have stated is if you disagree with the currently held theories you must provide convincing evidence."

Convincing to ... you ... ? To whom? If somebody isn't convinced by something, is that because it is unconvincing? And besides all of that, what can make a pseudo-skeptic read something and actually try to learn it?
Mr_Science
2.3 / 5 (12) Oct 15, 2013
I will not play word games, good day sir.
Humpty
1 / 5 (9) Oct 15, 2013
The other fun thing is that OK - mountain meets 50 billion, trillion lightning strikes = pile of rubble.

But why is it happening?

The aliens are levelling the earth, and when it's dead flat, all the land is under 200 meters of ocean, and the depth is the same all around the world - then they will invade us.