Impact that killed the dinosaurs?

JimC said:
Also, at 300 feet deep, the broadcrested weir equation is a bit out of its depth (sorry, couldn't resist).
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Funny!...:LOL:
Thanks. Yep, there are probably a number of equations and calculation involved with my question.
Still, an inflow of 8 hours shows the amount of energy that was released by the impact.
 
"amount of energy"

Yes, a wall of water 377 miles long, 300 feet high, going 50+ feet per second for close to 8 hours.
 
"Still, an inflow of 8 hours shows the amount of energy that was released by the impact".

That inflow calculation was just a SWAG on my part, but even if it weren't, no it is not really an indicator of the amount of impact energy - the inflow energy is only a miniscule percentage of the impact energy.
 
JimC said:
Well, curiosity overwhelmed me. I just did some very rough calculations based on loose assumptions that are subject to substantial error.
I came up with 83 hours to fill the basin with seawater and silt, assuming that the outer rim acted as a broad crested weir and the surrounding sea locally was about 300 feet deep. Incoming water velocity over the rim averaged a little over 50 feet per second, so was highly erosive. Incoming rate of flow was about 15,000 cubic feet per second per linear foot of rim perimeter. I consider this time estimate to be quite conservative and think it would probably fill much quicker (but still rather slowly in terms of hours required). A caveat - I didn't check my numbers or arithmetic and could be way off even if procedurally correct. And yes, I am aware of the potential errors in the assumptions I made.
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Yes. It would also make perfect sense if the basin took decades to fill. Or millennia, if the climate was dry (was it?).
If the crater depth was 1 km, what was the height of the crater rampart above the surroundings?
 
"Yes. It would also make perfect sense if the basin took decades to fill. Or millennia, if the climate was dry"

Since it was a sea impact completely surrounded by a wall of sea water, I doubt that it took decades or millenia to fill no matter what the climate was.

"If the crater depth was 1 km, what was the height of the crater rampart above the surroundings?"

I did the two refill time estimates based on two reported crater size projections and assuming that the associated volume calculations were based on idealized spherical segments (we all know that isn't actually the case, and this approximation ignores rampart and central rebound heights)

The long refill time was based on a crater 110 miles in diameter and 12 miles deep.
The short refill time was based on a crater 200 km in diameter and 1 km deep.
The volume equation used was
Volume= pi*[crater depth]*(3*[crater radius]^2+[crater depth]^2)/6
Associating the long refill time with the 1 km depth sort of mixes apples and oranges, so I didn't do that.
 
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JimC said:
"Yes. It would also make perfect sense if the basin took decades to fill. Or millennia, if the climate was dry"

Since it was a sea impact completely surrounded by a wall of sea water, I doubt that it took decades or millenia to fill no matter what the climate was.

"If the crater depth was 1 km, what was the height of the crater rampart above the surroundings?"

I did the two refill time estimates based on two reported crater size projections and assuming that the associated volume calculations were based on idealized spherical segments (we all know that isn't actually the case, and this approximation ignores rampart and central rebound heights)

The long refill time was based on a crater 110 miles in diameter and 12 miles deep.
The short refill time was based on a crater 200 km in diameter and 1 km deep.
Associating the long refill time with the 1 km depth sort of mixes apples and oranges, so I didn't do that.
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It kind of makes me sad that few of the non avian dinosaur species didn't make it.
 
Baylor, you posted a quote of me before I completed my edit.
Do me a favor please, and quote the final version of my post.
Thanks

And yeah, I wish some of them had made it too (though that would also increase the likelihood that we wouldn't be here).
 
JimC said:
"Yes. It would also make perfect sense if the basin took decades to fill. Or millennia, if the climate was dry"

Since it was a sea impact completely surrounded by a wall of sea water, I doubt that it took decades or millenia to fill no matter what the climate was.

"If the crater depth was 1 km, what was the height of the crater rampart above the surroundings?"
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Well, to figure out, millennia or more.
If the water around was 90 m deep and an impact forms a crater 1000 m deep with a rampart on average, say, 300 m above ground then the rampart is on average 210 m above sea level. If the rampart level varies between 200 and 400 m above ground then the rampart is at peaks 310 m above sea level and at low points 110 m above sea level.
If the climate is wet, the crater would fill with a freshwater lake that eventually would overflow the lowest point of rampart. With 1000 m depth, it would take region of thousand year.
If the climate is dry, a salt lake would form in crater bottom. Eventually the rampart would get breached somewhere either by landslide or by headward erosion of internal drainage river capturing the sea.
 
That assumes the rampart is going to be uniform in minimum elevation with nothing below sea level. That doesn't happen.
Note the erosion gouges in the actual crater (and yes, I am aware that this is a gravity map).
ROC_CB2-263bamf.jpeg.jpg
 
Another recent study highlighting how the Deccan Traps was already causing a mass extinction event before the Chixculub impact:

phys.org

More than a meteorite: New clues about the demise of dinosaurs

What wiped out the dinosaurs? A meteorite plummeting to Earth is only part of the story, a new study suggests. Climate change triggered by massive volcanic eruptions may have ultimately set the stage for the dinosaur extinction, challenging the traditional narrative that a meteorite alone...
phys.org phys.org

What wiped out the dinosaurs? A meteorite plummeting to Earth is only part of the story, a new study suggests. Climate change triggered by massive volcanic eruptions may have ultimately set the stage for the dinosaur extinction, challenging the traditional narrative that a meteorite alone delivered the final blow to the ancient giants.

...

"Our research demonstrates that climatic conditions were almost certainly unstable, with repeated volcanic winters that could have lasted decades, prior to the extinction of the dinosaurs. This instability would have made life difficult for all plants and animals and set the stage for the dinosaur extinction event. Thus our work helps explain this significant extinction event that led to the rise of mammals and the evolution of our species," said Prof. Don Baker.

...

The study involved researchers from Italy, Norway, Sweden, the U.K., the United States and Canada.
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This came up in another recent articles:

TL;DR: The key fossil sites for the impact period are in the US, Canada, and China - and the Chinese ones show a long decline among dinosaurs over a few million years before the asteroid finally hit.
 
Brian G Turner said:
The key fossil sites for the impact period are in the US, Canada, and China - and the Chinese ones show a long decline among dinosaurs over a few million years before the asteroid finally hit
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It sounds a bit like that quote from Hemingway's The Sun Also Rises:
'How did you go bankrupt?' Bill asked.

'Two ways,' Mike said. 'Gradually and then suddenly.'
Click to expand...
 
Danny McG said:
I don't agree with this big impact theory, I've seen One million years BC and it's obvious that the overgrown lizards couldn't compete with cavemen brandishing spears.

View attachment 114993
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And It had Raquel Welsh is a very skimpy animal Hyde bathing suit. She was bay far the best special effect in that film . :D
 
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