From the University of the Witwatersrand
New evidence on lightning strikes By Kanina Foss
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.
Image: fir0002 | flagstaffotos.com.au
In a world where mountains are crucial to food security 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 compass to prove – for the first time ever – that lightning is responsible for some of the angular rock formations 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 magnetic field, 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 lightning strikes 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.
Image: Professor Jasper Knight
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 rock surface and making mountain landscapes even more vulnerable to weathering by lightning 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.
In re human boots eroding mountains. My 1966 trip was the John Muir Trail north to south through the thaw in July. At that time the Trail used the meadows, and was obvious for the four feet deep trenches of dirt carried away by boots and hooves. Now the Trail stays up on the rocky sides above the meadows.
On information and belief, twenty-five-thousand hikers annually used the Trail until the traffic was limited by permit requirements. When I walked, thirst was slaked face down in a pristine creek. Remember that one can never go home again.
The Mazamas’ Mountaineering – The Freedom of the Hills had good advice on lightning.
Very interesting. Thank you for this, Anthony.
I guess this makes sense though I hadn’t thought about it much before. My scepticism starts with the statement that lightning strikes “can cause boulders weighing several tonnes to move tens of metres”. Does anyone have an idea how many orders of magnitude there are between “boulders weighing several tonnes [moving] tens of metres” and, say, the rest of the mountain?
Assuming a smallish, conically shaped mountain with a height of 1000 m, a slope of 45 degrees and a rock density of about 2.7 x water, I’m getting a mass in the range of 3 E9 tons so that’s nine orders of magnitude. I’m struggling to see that the effects of a lightning strike – or even lots of lightning strikes over time – as “significant”.
Lightning strikes the Earth ~10 per second, every second of every year. That over 300M times per year, year after year.
Why would bloggers at this site make fun of this papers observations?
No wonder sea level is rising, it’s being infilled faster with global warming causing more lightning and therefore faster infill. Gimme my Nobel now.
The Drakensburg. One of the most beautiful mountain ranges I have ever been in. The formations are so varied. Breathtaking. Most of the people live in round huts.
When I first read the article I thought it was interesting and possibly of some merit but, after reading the post by Tom G(ologist) [says: October 15, 2013 at 12:04 pm] I think the article is of doubtful merit.
Thanks Tom, for the “enlightening” information.
Tom: any thoughts on the possible action of lightning by rapidly vaporizing moisture contained within rocks and causing pressure fractures which could lead to more rapid erosion? Worth mentioning or old news?
kingdube says:
“Why would bloggers at this site make fun of this papers observations?”
Because this paper cannot support its assertions.
We are mostly skeptics here. That means any paper presented must stand on its merits. But as you noticed, this one is having a hard time.
Nothing new for the guys of the Electric Universe theory. The surface of planets and moons tells the story of lightning on a cosmic scale.
@Tom G(eologist). Sadly it appears that their paper has been “peer reviewed” and therefore now deemed suitable for publication and further citation… What is peer review for if not to stop folks from embarrassing themselves? Sad, truly sad.
Sounds about right, although the link to climate change is dubious at best. Electricity is an incredibly powerful force that is much underestimated.
I wonder why he’s using a compass to detect where the rock has been struck and melted. You would think that there would be pretty obvious visual signs if this happened…
I believe some creative journalism was also involved here. Certainly lightning is a erosive factor but to dismiss water and ice as the prime erosive factor is ludicrous.
http://www.gold-dna.de said on October 15, 2013 at 2:14 pm:
Indeed. Unfortunately the evidence of the cosmic lightning strike impacts greatly resembles that of impacts by non-energy objects, including the erosion craters from the vaporized material looking like impact craters, with deposition of dusts formed at high temperatures, etc.
Although it is perplexing how celestial objects exposed to the same influences such as solar magnetic field and solar wind, can develop such massive yet opposing static charges that inter-celestial object lightning is even possible. Were the protons (aka atomic hydrogen as a plasma) swept away from Mercury and Venus by the solar wind caught up in the Earth’s strong magnetic field, giving the Earth a strong positive charge?
Oh wait, I got it! There is electro-magnetic friction that builds up the static charge as the objects pass through the electro-magnetic aether, the lightning strikes are between the aether and the objects, not between the objects themselves as may mistakenly be believed. Is that it? Come on, that’s got to be it!
And here I thought it was the Koch Bros. that took the tops off mountains.
@ur momisugly kadaka
http://www.thunderbolts.info/wp/2013/10/14/daughter-of-uranus-2/ …
… and there are many more examples on that website that tell a different story than asteroids and meteors, like this one:
http://www.thunderbolts.info/wp/2013/10/06/electric-fossils-and-thundercrabs/
Basalt? Serpentinite and magnetite can form as an alteration of basalt (olivin). I have seen this in the field attracting the compass needle to the rock when held close. Suppose they did not know.
Geophysicists have known about the various forms of rock magnetism for a long time. Ask them, rather than geographers.
The economic implications would seem rather tiny.
If one reads the actual article, one will see that the press release posted above is quite dumbed down, even to the point of not presenting the same thing as the article. The ludicrously dismissive comments are understandable given the content of the press release.
In fact, the article makes very little mention of climate change; rather, it states that using climate as a proxy for mountain formation may, in fact, be wrong. The article presents a different view of how they used magnetisation. After finding possible lightning strikes, the authors waved a compass across the site and found that it deviated towards the centre of the strike.
On reading the article, it appears to be a qualitative first attempt, and seems quite reasonable. It is the sort of article that should provoke further, perhaps quantitative, research.
So what do do you do when you are faced with the dilemma of mitigation or CO2 reduction and sequestration: put in a few dozen $100 lightning rods or build thousands of windmills, shut down all fossil fuel burners, kill off the cattle, vegetarians and wildlife, stop agriculture and mining…. Surely South Africa wouldn’t make the IPCC proponents’ choice.
Michael D says:
October 15, 2013 at 10:06 am
“They put in that phrase about climate change because it helps the paper get accepted – makes it more topical in the eyes of the reviewers. Sometimes called “pandering”.”
Hmm I found a different dictionary meaning for pandering that also fits:
“pan·der (pndr)
intr.v. pan·dered, pan·der·ing, pan·ders
To cater to the lower tastes and desires of others or exploit their weaknesses…”
Surely all geographers took the early retirement option in the 18th Century along with alchemists. What is a math and science illiterate professor doing with a geological hammer and a compass? Comon, get back to coffee-grows-in-Brazil type stuff that you turned to when the world mapping was over with (and done now digitally). He read somewhere that when basalt hardens, the magnetic minerals align themselves in the magnetic field directions of the time. How can you have angular blocks AND melting with (time for) recrystallization of the minerals realigned because of the lightning – you would have volcanic glass. I hope the geology department has this dufus straightened out!
Hmm. Interesting idea; another force in geomorphology. T(om)Gologist: I do not believe the Drakensberg is MORB. It is tholeiitic, but more akin to Snake River or Siberian plateau basalts (still, a spreading-related volcanism, but in an intercontinental location). These, when they cool rapidly may develop strong remanent magnetism (which the authors here say can affect their magnets, at least on the site). Their idea is that the lightning strike heats the minute particles of magnetite or other magnetic microminerals, which erases the original magnetic signature, and lets it the assume a new magnetic signature (today’s magnetic field). If they can map it, then it’s real. The extent to which lightning blasts actually affect the topography is to be determined, but one assumes it has some effect on things. Perhaps it just eases the way for water to do its work, forming cracks subject to flow and freezing-thawing conditions.
@ur momisuglyJarryd I agree, I have seen some spectacular damage done by lightning , @ur momisugly some others, it is fine by me to be skeptical but when it becomes mocking then it does not sit well with me.
I also agree with the description that translates Burg into lair, as far as I can remember my Dutch language it can also mean bastion, (back in the Middle Ages) there were many towns in Holland that ended with ,…-burg, and still do today, there are historical sites of castles and or retreats that use that ending as well.
In principle the effect of lightning on anything is not dissimilar to spark erosion. A technology widely used to form metal shapes in plastic mold making. In practice the sparking rate in mold making is very high but the progress is very slow.
In nature the sparking rate is very low and the spark erosion is not significant.
Well part of the fun of watching puzzling things in life, at WUWT, is that no matter where it turns; there always seems to be somebody who has been up to his earballs, in whatever, has just run across the bottom of the screen, and hears alarm bells ringing.
Now I know about enough of the English language to be able to read all those big words longer than four letters in that post by Tom G(ologist), and think; I’ll have one of these, and two of those; but bottom line is, that other than possibly having seen some of them in an old Scientific American article; not necessarily together, I don’t have the vaguest idea of their significance, so I can just nod, and say; glad somebody out there knows this stuff, because I sure don’t.
Now I DO know the feeling; because if somebody throws down some trash on MY Youngest Dry Arse territory; well I get the same goose bumps that I sense that Tom got here. It’s embarrassing when that happens, because we all think that everybody should understand OUR sand box, as well as we do. But of course, that’s not possible; we don’t have room for all that Pyroxene, so we all just take far too much for granite.
Well WUWT is not the place to float any chaff, because there’s always a Tom G(ologist) of almost any species, to throw the red flag.
And to think, that just hours ago, I took the trouble to look up the phase diagram, for the Si-Ti binary system, because some guy asked (elsewhere) how to make that stuff amorphous; well he wanted to know what temperature to cook it at. Wasn’t a problem; you can just look that up in a book (which I have).
So thanks Tom G for the tutorial; I’m now working on the five and six letter words.
George
Sounds like Crop Circle “research”.