HUGE Aussie asteroid impact sent TREMORS towards the EARTH'S CORE Australia is home to the largest asteroid impact crater on Earth. The 400km-wide crater is more than twice the size of the Chicxulub crater in Mexico, which is often attributed with wiping out the dinosaurs. The new find in the Warburton Basin in Central Australia is a stunning 400km-wide impact zone from a huge asteroid that …
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We may be overestimating the effect of the asteroid and underestimating the effect of other factors. The Cretaceous extinction event coincides with the Deccan traps eruption. According to quite a few palaeontologists and geologists, the unpronounceable and unspellably named boulder hitting the gulf of Mexico is just the "final straw". The extinction was already on the way courtesy of the Deccan traps. It only accelerated it.
The great dying before that (240M years ago) coincided with a similar eruption (in Siberia if memory serves me right). And so on.
Also, it depends on how it hit - angle, velocity, etc and what did it hit - shallow sea, earth, etc. Dunno, it will take quite a lot of digging until this gets into the textbooks on par with Chicxulub. I just hope they do not name it as unpronounceably too.
I've sometimes wondered of the Deccan traps event was caused by the Yucatan impact - they're about 180º apart on the opposite side of the planet. I can imagine a simplified model of the earth's structure that would allow this but can't see how it could be propagated through the planet as we envisage it.
"angle, velocity, etc and what did it hit"
There's only a limited range of velocities for most asteroids (vs comets) hitting a planet: 1x to 2x the planet's escape velocity. An asteroid approaching a planet from "astern" will probably have a low initial velocity relative to the planet and be accelerated to the planet's escape velocity by the time it hits. Crossing and head-on impacts add the asteroids' higher relative initial velocity to the planet's escape velocity, but such asteroids - given the range of asteroid velocities in the Solar system - aren't going to be much higher than Earth's escape velocity.
Comets have a wider range of velocities because they pick up quite a head of steam as the drop into the inner system.
From what I can tell it is not impossible that the Deccan Traps were antipodal to Chicxulub- the asteroid hits and pushes such a forceful wave through the planet's core that it bursts out at the nearest available point on the other side. If this was to be correct then the Siberian Traps may be antipodal to another impact somewhere in the southern hemisphere. I don't know how Siberia and Australia were positioned relative to one another at that time, though.
Most of the output of the Deccan Traps is under the Iridium layer, so comet causing the eruptions can be safely be ruled out.
Current hypothesis is that the Traps were erupting for quite some time before the Chicxulub strike, with fossil evidence supporting the idea - there was a dieoff underway for some period before the iridium layer appeared.
Under normal circumstances, Chicxulub should not have been a global extinction level event, even with the added input of the Deccan Traps. The final straw is that at the time it was a shallow sea with a _huge_ layer of limestone underneath and most of that got vaporised, putting an enormous CO2 pulse into the atmosphere along with billions of tons of water vapour.
This underscores that it's just as important where a rock hits as to the size of it (Modelling large ones shows that land strike = bad, open ocean strike = worse, shallow sea/continental shelf = even worse still)
For local extinction levels, there may not even be an observable crater. There at least one hypothesis that the younger dryas dieoff in north america was caused by a fragmenting comet skimming the atmosphere, generating a shitload of airbursts that effectively sterilised the surface - https://craterhunter.wordpress.com/ - I can't fault the idea and there does seem to be a fair bit of supporting evidence including melted rock formations in Mexico which appear to have been windblown into their current shapes whilst molten.
As others have said, the australian crater was known, but not the multiple large lumps. It's probably not large enough to have caused a global extinction level event though, especially given that life at the time was extremely simple.
The Deccan traps aren't the only ones associated with a dieoff - the much older Siberian traps are also about the same age as a dieback.
Personally I wouldn't be surprised if most of the larger craters caused by fragmented impacts rather than a single solid one - Shoemaker-Levi9 serves as a good observed example - but they're generally so badly eroded that it's impossible to tell.
From a human point of view, extinction level events aren't needed to wipe out civilisation. There are plenty of rocks whizzing around the inner solar system which are large enough to do the job and enough of them come worryingly close each decade that as a species, we really should be making plans to get off this planet.
The Chicxulub impactor was particularly devastating because of where it struck, on thick strata of both carbonate rocks and gypsum (calcium sulphate). Vaporised, these injected vast amounts of sulphur dioxide and carbon dioxide into the atmosphere. The sulphur dioxide would have formed sulphuric acid clouds that would have reflected much sunlight, causing far worse global cooling than mere dust from silicate rocks. Over the next decade it came back down as acid rain. And then after a brief spike of global cooling, the sulphur was gone leaving the carbon dioxide to caues global warming. This massive two-way fluctuation was probably the last straw for lumbering great dinosaurs. (The small flying ones did survive - we now call them birds).
This on top of a global environment already seriously degraded by the Deccan Traps erruptions.
Not just the geological effects either - there was quite a lot going on leading up to the extinction of the dinosaurs whose numbers were in decline long before the deccan traps and the KT event. One of the hypotheses I found very interesting was the possibility that the appearance and rapid spread of the grasses and hardwood trees 100-60Ma ago reduced the amount of food available to the dinosaurs, since they're much more herbivore-resistant.
In essence, big-ass rocks falling out of the sky are pretty terrifying but you'd best be nice to your lawn.
"Who knows what could have arisen in the present day if it were not for things like this?"
Or might not have arisen. Each extinction event led to evolutionary radiation as life recovered. Without the extinctions life would have been more stable and fewer new designs would have appeared. For instance the mammals got nowhere until the dinosaurs were removed.
"We don't need to theorise what would have happened if dinosaurs had evolved brains, we can just look at crows"
That doesn't really work though. The evolutionary pressure was different after the extinctions.
Beforehand, there was evolutionary advantage in biggness - and being good at eating other things. So we had plenty of hugeosauruses and hungrysauruses. But was there an evolutionary niche for a brainysaurus? Someting like the Jurassic Park version of the velociraptor perhaps? Mid-sized, so needs to use other abilities to avoid getting eaten. By cooperative hunting perhaps, which might lead to the development of language and tool using. Given the right physical evolution. Just think how much better the Natural History Museum would be, if some of the dinosaurs were carrying rifles?
Hypothetically, if a group of dinosaurs had developed technology, there would be little or no evidence of it.
If we were wiped out today by a big flying rock the only proof that we ever existed on this planet, after a few million years, would be chunks of kit we lobbed off of it.
Anyone spotted any dino-tech on the moon?
Diamonds aren't very big, tend to be brittle & can be erroded and what connects them would dissolve or corroded in a blink of a geological eye.
Pottery has a hard enough time trying to survive a mere couple of thousand years.
Concrete seems to rot pretty quick in geological terms and how would a future society distinguish concrete from a compressed water bed?
As a species we've only been kicking around for a blink of an eye compared the our lizard forebears, which means less opportunities for stuff to find its way into the strata thus increasing the likelihood of a future species discovering our existence. The moon buggys had the best chance of being discovered because it is in a safe, oxygen deprived, geologically stable place with little or no environmental mechanical wear. The real sod would be that the future species would need to spot it, after all its a big rock a long way away.
Fossil remains of civilisation: the ones that you will find intact in vast quantities after tens of millions of years are fired clay artefacts. House-bricks and pottery, complete with maker's marks and glazed decorations.
Many other things will fossilize like shells: the original will disappear but the hole in the rock will fill with some other mineral (often quartz, calcite or iron pyrites). This will include some truly vast fossils: sewage pipes and railway tunnels!
Gold and silver jewellery will survive but whethre any will be found is quite anothr matter. There's not enough of it.
Pottery lasted forever. Forever. Admittedly in shards, but once a pot is made, the shards stay until the earth is no more. Go to any ancient site and you will see. I have walked the acres of Sarai (capitol of the Golden Horde), as an example, and the pottery shards on the surface are like a gravel drive. And that's just the loose stuff. There are Greek sites and Cathagenian sites with the same density, if they've not been dug up and built over.
Hypothetically, if a group of dinosaurs had developed technology, there would be little or no evidence of it.
This forms part of the basis behind a pleasantly readable science-fiction book called Toolmaker Koan. There's one scene where the humans are working with the 'aliens' onboard their ark looking at a map of modern Earth and suddenly the moon comes into view. The 'aliens' recognise it and realise that their ark didn't carry them very far after all. Quite poignant.
@ Dewix
I don't know how fast material degrade in space. What I do material in space does degrade with time. If any reptile type of civilization was in place all its monuments on Earth are long since turned into dust.
As for space, there is always a chance something might remain, while not in working state, at least in highly degraded state. If this actually happened I don't know, the interesting fact however is that it only took the human race around 10 million years to evolve to current state. So this might have happened more than once and more than twice. Since 65 million years is a long time.
I'm not really up on Archaeological Science, but it does continue to suggest that the evolution of all life on this planet has been set back a good few times.
99% of species that have existed have gone extinct. Makes ya think a bit that does. My thought is 'it's time we got off this rock' ;)
concerning deadly animals and other natural events, Australia cannot be beaten by Mexico.
On a more serious note - there have been quite a lot of mass extinctions in the past. This one could be connected with the P-T event 250 million years ago, also called the "Great Dying". Until someone figures out the exact age of the impact this is all speculation, of course.
If sufficient research is ever carried out they might find evidence that the larger impact was the result of an innocent Sperm Whale impact. The other crater will, of course, contain residue from a bowl of Petunias. Not impossible - just infinitely improbable.
"Geophysical modelling of the Cooper Basin, which overlies the eastern Warburton East Basin, suggests existence of a body of high-density (~ 2.9–3.0 gr/cm3) and high magnetic susceptibility (SI ~ 0.012–0.037) at a depth of ~ 6–10 km at the centre of the anomalies. "
It's a rule of science fiction that anyone who drills into the earth's crust in order to do 'geothermal research', is either lying and it's actually a secret government project to cause earthquakes, or dies horribly due to alien/supernatural horrors hiding at the bottom of their shafts.
It's a bit like going to an old isolated house/castle for help after your car has broken down in the rain. Something you just shouldn't do.
You've clearly never played Chicxulubby-Spoony before.
And I couldn't let that go by without mentioning one of my favourite Fast Show sketches courtesy of Carl Hooper. Please don't click if you might be offended by some brits doing aussie accents and a few colourful metaphors.
https://www.youtube.com/watch?v=TAj7S7lyHdA
Any Earth collision that formed the moon would have happened much, much earlier. That kind of impact would have wiped out all life except possibly for a few very resilient bacteria, and there would be very little record of anything that happened before it.
I thought about this, too. But then it occurred to me that Moon would have been formed over 4 billions years ago, when Earth did not even had (much of) crust. It must have been all pretty fluid at the time, which is exactly what allowed the Moon to form into a nice round shape - and Earth not to lose its round shape, too.
well not exactly "spew forth". The theory is that early on in the solar systems the proto-earth collided with another planet, smashing and liquidising both and that the remains formed the earth/moon combo. But that is far, far earlier than this. The moon was then liberally clobbered by impacts in the period known as the late heavy bombardment. The earth would have been as well but that was circa 4,000 MY back.
Wow, I don't know why I was down voted, because I did say it was a silly question.
Oh well.
Here's another silly question.
We know that the continents (land masses) have shifted to their current position today from where they would have been millions of years ago. Would it matter where the asteroid hit? In lets say a center of a plate compared to an edge?
Again, I haven't a clue, just asking...
What does that headline actually mean? How in any sense are these cracks near the Earth's core? Yes they go 20km down, but that really isn't significant. It is like saying Wales is near the USA because from the perspective of England they're in the same direction!
The story is interesting enough without that. These lying headlines make me distrust the rest of the article.
Dewix > "Diamonds aren't very big, tend to be brittle & can be erroded and what connects them would dissolve or corroded in a blink of a geological eye."
However, zirconia are very robust, many having survived repeated tectonic activity. So, althogh also tiny, a cut and fashioned zircon gemstone could theoretically survive the many millions of years necesary to provide evidence of dinosaur techniloigcal advancement. Assuking they wore jewellery.
http://www.amnh.org/education/resources/rfl/web/essaybooks/earth/cs_zircon_chronolgy.html
> "a few grains of zircon found in the early 1990s in a sandstone from western Australia dates back 4.2–4.3 billion years"
> Assuking they wore jewellery
Ridiculous. They didn't even have opposable thumbs, how would they even put on a ring? Or earrings without ears? Belly button piercings on a reptile? Complete and utter nonsense!
Those Triassic Swarovski crystal salad bowls however are a dead giveaway, not to mention the collectible "Triceratops Toddlers" figurines unearthed in Cretaceous shales. Jewellery no but they were first on the planet to have their civilisation collapse due to a Franklin Mint Horizon.
I love all the imagination flowing here but you guys do realize that since DNA was discovered and has been well studied, that organisms do not evolve upward? We are way past the "simple cell that evolved in a pool of goo". It has been extensively observed and quite well documented that mutations are not positive and uplifting (please don't tell me about computer models that show an upward march toward perfection, lets just stay with observable science). It has also been observed that our human DNA is degrading not improving (this is one of the reasons why we should not have children with our siblings). We currently use science to identify ways of keeping us healthier and better nourished but on a cellular level we are headed for destruction. But dreaming is what we humans do and the imagination is a wonderfully creative thing. Let's just keep perspective and leave the dogma behind.
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