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Bobby

The Chicxulub impact 65 million years ago, did it kill the dinosaurs?

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Maybe the greatest detective story - around 65 million years ago the dinosaurs (expect birds which most now regard as a group of dinosaurs) who ruled Earth for around 150 million years suddenly vanished along with ~75% of all life on Earth in one of the greatest mass extinctions in history.

 

Over the past few decades evidence has grown that the cause was a giant asteroid ~7-8 miles in diameter that hit the Earth off the coast of what is now the Yucatan peninsula in Mexico, forming the huge ~150 mile wide Chicxulub impact crater. Dating proved it was around 65 million years old, the same age as the mass extinction.

 

Posted Image

 

The 7-8 mile wide asteroid, heavier, bigger than Mt Everest, travelling at ~60,000 mph - 25 times the speed of a rifle bullet - struck the Earth at a ~30 degree angle from a SE direction. The energy from impact was around 100 million megatons of TNT - about 5 billion Hiroshima bombs, 6 million Mt. St. Helens eruptions or ~10,000 times the world's nuclear arsenal at the peak during the Cold War. The initial fireball would have incinerated all exposed life almost instantaneously 500-1000 miles from ground zero and caused a magnitude ~12 earthquake which triggered volcanic eruptions and secondary earthquakes and tsunamis worldwide.

 

A superheated rock vapour cloud and blastwave radiated outwards perhaps thousands of miles, killing everything exposed. Tsunamis hundreds of feet high radiated across the planet swamping coastlines for miles inland.

 

The impact ejected trillions of tonnes of vapourised rock, asteroid into space which then resolidified, encircled the Earth and fell back into the atmosphere. The smallest particles burnt up in the upper atmosphere, heating it to around 2,000-3000c across the planet, causing the entire sky to glow red hot, heat which then radiated back down to the surface heating it by up to 500c or more for several hours. This heat radiation killed almost all life directly exposed and caused almost all Earth's vegetation to combust triggering huge global wildfires. If the heat pulse didn't ignite the vegetation then falling larger pieces of material would. Virtually the entire Earth's biosphere on land would be incinerated within perhaps hours.

 

Smoke from burnt vegetation and ash, dust and other particles ejected from the impact encircled the Earth, plunging the entire planet into darkness for up to a year or more. Being unable to photosynthesise the algae and phytoplankton which forms the basis of the Ocean food chain died, causing the Oceanic ecosystem to collapse, wiping out most life in the Oceans as well. With a year of darkness temperatures plummeted and much of the planet from pole to pole fell below freezing, entering a brief ice-age.

 

As the asteroid impacted rock containing limestone and gypsum, massive amounts of sulphur were released into the atmosphere which when combined with moisture  (increased by billions/trillions of tonnes of vapourised water due to the impact in a shallow sea) formed sulphuric acid rain as strong as battery acid which then rained down on the surface, poisoning the soil, lakes, rivers and shallow seas.

 

When the skies cleared an extreme greenhouse effect took hold due to the carbon dioxide released, causing large scale global warming for centuries or millenia.

 

Some have blamed other events going on at the time as a major factor in the mass extinction, such as volcanic eruptions in the Deccan traps but they had been going on for perhaps a million years or more before the impact and there is no sign that life on Earth was on its last legs or that there was a major effect at all. Other factors might have caused some declines amongst dinosaurs and other life but there doesn't seem to be evidence they would ever have caused a mass extinction. The apocalyptic effects of the impact event alone seem sufficent to explain the mass extinction, Deccan traps, climate shifts etc or not.

 

So to me the impact theory seems to be most logical explanation. Indeed a panel of the worlds top experts came to conclusion that the Chixculub impact was the cause of the mass extinction in 2010 and recent evidence seems to confirm the idea yet further.

 

http://news.bbc.co.uk/1/hi/8550504.stm

 

I wonder if such an event happened today, would humans also go extinct?

Edited by Bobby
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I've often wondered whether it was a combination of the Deccan-Traps eruptions and the Chixculub impact.

 

The answer to your last question is "Yes".

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I've often wondered whether it was a combination of the Deccan-Traps eruptions and the Chixculub impact.

 

The answer to your last question is "Yes".

Good answer...But, wouldn't a race of chinless wonders emerge from the catacombs a few years' later?

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Good answer...But, wouldn't a race of chinless wonders emerge from the catacombs a few years' later?

 

Probably and they would no doubt all go to Eton.

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Good answer...But, wouldn't a race of chinless wonders emerge from the catacombs a few years' later?

 

You've done it again Pete, an interesting post by Bobby does not need a silly political replyPosted Image

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I suppose some would survive the initial effects by sheltering undeground in bunkers and tunnels, especially if we had some warning and time to build and prepare, stock up on supplies etc for a year until the skies cleared. Surviving the aftermath would be tough though as people emerged onto the surface of a blackened, charred, poisoned almost lifeless planet. Finding food to eat would probably be the biggest challenge. No crops to grow, no plants to eat, no animals to hunt, probably no seafood either as the seas would be largely dead. Starvation was what probably finished off many of the survivors the last time, nothing larger than a cat survived - so food requirements was likely a big factor in survival. Global warming, pfft, now this would be something to worry about!

Edited by Bobby

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Political, moi?

Indeed but dinosaurs extinction events, asteroids, and growing  carrots don't really need it.

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Indeed but dinosaurs extinction events, asteroids, and growing  carrots don't really need it.

So where did he make a political comment about growing carrots?

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Indeed but dinosaurs extinction events, asteroids, and growing  carrots don't really need it.

So, supposing there was an asteroid impact sometime next week, who (if any) would you expect to survive? Because, my guess would be that the best chance would be handed to those least capable of fending for themselves - a very different type of genetic bottleneck to the one our species is thought to have previously survived...And, do you really believe that the spectre of politics wouldn't cloud people's ideas, on how to proceed, following such a global catastrophe?

 

Because I, for one, have no doubt at all that it would: IMO, we'd be in a real-life Mad Max movie!

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So, supposing there was an asteroid impact sometime next week, who (if any) would you expect to survive? Because, my guess would be that the best chance would be handed to those least capable of fending for themselves - a very different type of genetic bottleneck to the one our species is thought to have previously survived...And, do you really believe that the spectre of politics wouldn't cloud people's ideas, on how to proceed, following such a global catastrophe?

 

Because I, for one, have no doubt at all that it would: IMO, we'd be in a real-life Mad Max movie!

 

 

Being a member of the  illuminate I can assure you that no chinless wonders will be allowed in(location yet to be decided)

You must realise that Cameron,clegg and balls are not great breeding stock, but  to his credit  call me dave  did say he was better looking than the rest but sadly still a no.

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