Fun pedantic fact! The Tertiary period has been officially divided into the Paleogene and Neogene periods. So it’s a K-Pg Level Extinction Event, not K-T.
PDF link: http://www.stratigraphy.org/upload/ISChart2008.pdf
Nit, picked. 
Good Gawd…just imagine what a K-R or heaven forbid a K-XXX event would look like then. If you didnt go blind you would most surely need strong glasses.
I’ve heard this too, but never understood it.If the destruction was so vast, all life would have been extinct within days or weeks. But the KT period is measured (I think) in geologic time–centuries, or thousands of years… and many species survived it .
Now, animals eat every day, not once a century.If the plants were burned, or the sky darkened so that they couldnt grow, then ALL the animals of a species (which eat that plant) would die within days or weeks. Not 90% of the individuals, but all of them.
What am I not understanding here?
Nothing is ever as complete as we often think it is. For example, you might spray Lysol on a table and say “I sprayed the whole table.” And yet - at a microscopic level - there are going to little pockmarks that were sheltered, maybe a few bacteria colonies living under a layer of protective dirt and other small areas that, through sheer dumb luck, were missed by all the tiny aerosol droplets. There may even be a few tough microbes that survived the small dose they got of the antibacterial. That’s one of the reasons Lysol can’t claim to kill everything, but only 99.9% of everything.
If we use the same figure to look at a global catastrophe that destroys the “whole Earth” 99.9% is pretty terrible. Yet, 99.9% of humans leaves 6 million of us alive. 99.9% of a forest still leaves a square mile or more of surviving trees (perhaps in little patches, or perhaps in one protected valley that may or may not be part of the fossil record we see because of things like erosion).
Another key is that even if the entire land surface burned, that still leaves all of the oceans intact. There’s no way you’re going to get a forest fire going in a kelp forest. Well, not unless the kelp forest is in a body of water fed by the Cuyahoga River.
It’s one current theory of (some) mantle plume origins. The timing of the traps vs impacts vs extinctions always looked suspiciously coincidental, but recent modelling of the focusing of shockwaves from a killer impact seem to support the idea that an impact can cause a plume to form at the antipode. Google the keywords “impact-induced antipodal hotspot” for links to papers and the like. Of course, like anything in emerging science, there are people on both sides of the argument. Me, I’m pretty sold on a impact-volcanism combo-killer for at least the P-T and K-T boundaries. I’m liking the addition of volcanic-global-warming-induced bacteriogenic H[sub]2[/sub]Sas a topper for especially the Great Dying (Permo-Triassic extinction)
What’s special about five years? Is it a matter of atmospherics that enough matter would have settled to allow enough sunlight through for growth?
I guess I’m just wondering where that number comes from.
-Joe
At the two minute mark it looks like someone is firing the Grand Cannon.
-Joe
I’m no expert on this subject, but I know that evidence of soot has been found all over the world, but has there also been evidence of worldwide fire also? I know that forest fires several states away have caused hazy conditions where I live, so I can see how a K-T type impact would blanket the world in smoke/soot, but that’s not quite the same as a worldwide conflagration.
However, it would still be a pretty miserable time for the survivors.
With a big enough impact, you can turn the entire surface of the earth to lava. See “crustal tsunami.” Granted, this pretty much exceeds the parameters of a K-T level extinction event.
Five years is a “best guess” figure how long it would take for (a) sufficient particulates to settle out of the atmosphere to permit adequate sunlight to insolate plant life, and (b) plant life to recover. (Obviously the two phenomena are directly related.)