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.
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If you pass a compass over an area where a lightning strike occurred, the needle will suddenly swing through 360 degrees.
So if you look away while it is swinging – the needle will have completed a complete rotation precisely to the degree and you wouldn’t notice any difference between the lightning strike area and another?
This appears to be nonsense or more correctly non-science..
I don’t much at all about how this technique of using a compass to measure lighting strikes works, but this article says that it proves mountains are less stable than we think. My guess is that the word “proves.” is overstated. My guess is that more research is needed, as it always is.
So, mountains shred themselves by spitting electric bolts at the clouds! Huda thunk?
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.”
Give me more money.
this has vast implications, especially in the context of climate change.
Give me lots of more money.
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
Stop laughing and give me more money. Did you notice I said, “Huge” Maybe I should of said “Incredibly huge”
This is just terrible news. I wondered why mountain ranges disappeared so quickly in Southern Africa.
Seriously how stupid do they (the professors: Knight and Grab) think we are. Okay many have bought into the whole AGW scare. In the dark of the knight (lack of intelligence and truth) we (unscrupulous researchers) will grab your money.
I guess I should go see Pikes Peak before it gets turned into a pile of ruble by a strong storm
I once witnessed a lightning strike on small hill in Utah and found the contact point after the storm had passed. The rock was blistered and fractured. Once I knew what I was looking at, I realized that there were hits all over that hill. I’m not sure how the erosion rate would compare to frost action, but it’s certainly visible. I’ll have to look more carefully at the exposed rocke the next time I’m in the Drakensberg.
Especially in the context of climate change, huh? Would this matter if that wasn’t so boldly inserted? Why do I feel nauseated when I read a statement like that?
Mike Bromley the Kurd: Yeah, what he said.
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.”
Why the need to “do something about” a natural phenomenon?
Whew! Hard to know where to start. The breathless alarm conveyed by:
“where mountains are crucial to food security and water supply, this has vast implications, especially in the context of climate change”
Surely there must some tie-in to tropical diseases and ocean acidification too!
I’ve spent lots of time mapping geology along ridgelines and across mountain tops and I’ve been close to my share of lightning strikes. i’ve seen fulgarites (fused loose sand due to lightning strike), but I have seen absolutely no evidence that a lightning bolt “cause(d) boulders weighing several tonnes to move tens of metres”. Blowing a tree trunk to smithereens is one thing – moving big rocks is something entirely different.
I guess this is what passes for research in the School of Geography, Archaeology and Environmental Studies (no math, physics, or chemistry required, I suspect)
We had a cabin in the Medicine Bow National Forest in Wyoming when I was growing up, elevation +8000 feet. The lightning strikes were numerous and magnificent along the ridge behind the cabin and anyone could see the ridge’s topography was obviously marred by lightning. Thunderstorms were terrifying and sheepherders and ranch hands in the area would beat it to the cabin to get out of harms way. Nobody who valued their life wanted to out on the mountain when lightning was striking.
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”.
Yes, we must ensure that all phenomena are interfered with.
In ’66 I was on Glen Pass in the Sierra Nevada and had taken shelter from the rain under an overhang. Then our hardware started buzzing and sparking forewarning the lightning storm that was soon scattering rock chips all over the gully. We did notice that the angular edges of the gully attracted the bulk of the strikes. The storm lasted about an hour.
So now we know why the pyramids were built in the part of Egypt that never gets any lightning.
I don’t know, Saruman sure tore up the Redhorn Gate with lightning in Peter Jackson’s movie.
Which is just as reality-based as this article.
Yep..every time I fly over mountains, my compass spins, I get lost, fly in circles, crash, leave a mark on the rocks, live on ice water, eat my dead companions (who were alive yesterday). We need more money to study, monitor and possibly solve this problem. It’s becoming catastrophic aircraft grounding wreckage (CAGW) !
Someone should invent the “Gumby” award for the farthest stretch in a scientific paper to link their findings to climate change. Too bad really, the technique and finding is quite interesting but dragged into the basement with the grandiose presentation. I recall going on a 1/2 hour detour once while bush navigating. it was not until mentioning it to a friend that I learned of a magnetic anomaly in the area.
Wow… who woulda thought God used EDM to carve the mountains…
Now CO2 is going to destroy the world’s mountains. Is there anything that wicked evil man-caused CO2 can’t do?
Seriously- this sort of shallow transparent rent seeking stuff should make even AGW true believers cringe. But then AGW true believers think Peter Gleick is a hero…….
Well you oughta see what kind of hole a lightning strike can blow in a corn field, or a nice normally quiet Florida Keys bonefish flat. I’ve been far too close to both of those, but at least the bonefish flat, will eventually get fish on it again. Corn still grows in the field, but I ain’t never seen the lightning make a crop circle.
I’m prepared to believe the prof is onto something; but I would like to know more about they know for sure where a strike hit a rock.
So do all mountains need lightning arrestor rods ? Just what remedial action do they suggest?
These are actually very sensitive environments…..especially in the context of climate change.
it’s a rock you morons
The Mother of All Magnetic Anomalies:
http://en.wikipedia.org/wiki/Kursk_Magnetic_Anomaly
Mark S
October 15, 2013 at 10:01 am
says:
‘Why the need to “do something about” a natural phenomenon?’
Maybe, because we’re just about ready to hear that CO2, just like it supposedly amplifies water vapor in the atmosphere, also amplifies lightning strikes? Or perhaps we’ll have to eliminate electrical generation entirely because, regardless of how it’s generated, it inevitably increases lightning strikes (except in Washington, D.C. and Hollywood, where it can be offset by the purchase of ‘Lightning Offsets’). Maybe, to convince us plebeians to do without electricity, if they can’t make the price high enough, they can come up with a nice jingle, ‘lighting and lightning, they go together!’ And, for the elites lightning can fill in for the carbon trading market when it collapses, and it will, by substituting a lightning trading market. Never underestimate the new frontiers ecology science can point us towards.
@ur momisugly MJB
I agree. On a quick skiim of the paper it looks like a pretty routine geomorohological investigation, with none of the hyped rhetoric of the press release. I’m kinda wondering what relationship the writer has to the authors and university, since I don’t recall seeing the “Berg” written as “burg” in Africa — i.e., was this a foreign reporter looking for a story?. I’ve had press ask me about my research and try to make the stretch to climate change, but they lose interest when I decline to go there. I think these guys got caught up in the “excitement” of the PR opportunity.
Now an otherwise reasonable study (although @ur momisugly GeologyJim, I need to look closer at the flying boulder claim) is being shredded by the snarky of the WUWT readership, and the baby is getting thrown out with the bath water. The “non-science” claims should be made on a reading of the paper, not the press release.
Doug Huffman says:
October 15, 2013 at 10:11 am
Yes, we must ensure that all phenomena are interfered with.
In ’66 I was on Glen Pass in the Sierra Nevada and had taken shelter from the rain under an overhang. Then our hardware started buzzing and sparking forewarning the lightning storm that was soon scattering rock chips all over the gully. We did notice that the angular edges of the gully attracted the bulk of the strikes. The storm lasted about an hour.
This is to be expected, the static charge of the surface would create peaks for corona discharge at points and edges of the surface so lightning would hit (actually emanate from) those points and edges. So did those edges and points get caused by lightning or were they acting as corona discharge points?