More Evidence Supports Massive Asteroid Strike

InnerPeace Volunteers writes "From a BBC Sci/Tech article: The idea is that a giant asteroid about 10 kilometres wide, travelling at 90,000 km/hour slammed into the Earth at the southern margin of North America. This was a case of global devastation rather than North American catastrophe. The asteroid devastated pretty much everything."

Comments

Everything but the frogs

[corvi42]

Yes, it destroyed everything but the frogs, salamanders, and other very precarious fragile life forms which have existed pretty much unchanged for millions of years before this impact. That is just one of the many problems with this giant space-rock theory.

Now I'm not saying that this theory isn't very convincing, but its going to be a long time before we truly understand the nature of what happened during this massive impact. I'm not doubting that a massive metor / asteroid hit the earth and caused catastrophic environmental fallout, but the facts are far from convincing.

Frogs and salamanders and other small amphibians like these are very delicate fragile creatures which are very easily affected by even small changes in their habitats. They breathe and drink through their skin, and so absorb pretty much anything thats in the air and water. They are also very sensitive to light & heat conditions. If a massive environmental disaster occured that was so devastating that it wiped out thousands of species, including very large robust reptiles like dinosaurs, why did it not wipe out the many frog & reptile populations that have continued pretty much unchanged since that time.

Understanding the consequences of a massive explosion / impact of this sort is very important to us. We should understand thoroughly the consequences and the survival strategies that are important in a post-nuclear / post-asteroid fallout situation. The dillemma of the frogs is just one of the massively understated holes in our knowledge about such disasters, and the verdict on what really did kill the dinosaurs is far from conclusive at this point - despite what the popular media likes to portray.

Giant space rocks hitting the earth and causing massive fallout is a great story, and the media loves to play it up. It satisfies our thirst for biblical-type plague stories and apocalyptic premonitions, but as far as the science goes, its anything but conclusive. Certainly this meteor impact did happen at the same time as the beginning of the end of the dinosaurs, but we must remember that despite what you may remember seeing in Disney's Fantasia, they didn't all just drop dead in a matter of one symphony movement. Their extinction happened over a long period ( although geologically it might look quick ), and we are very far from understanding the ecological and environmental changes that came out of it.

Re:Everything but the frogs

[Anonymous DWord]

Maybe the salamanders were hiding in caves in Afghanistan when the asteroids hit. Those suckers are pretty safe.

Re:Everything but the frogs

[nels_tomlinson]

Many frogs are able to hibernate. I have seen frogs in the swamps in Fairbanks, Alaska, where the ground is permanently frozen. During the summer the top few feet thaw, and this eems to be enough for these frogs, or their eggs, to survive from year to year.

Re:Everything but the frogs

[rve]

Frogs and salamanders and other small amphibians like these are very delicate fragile creatures which are very easily affected by even small changes in their habitats. They breathe and drink through their skin, and so absorb pretty much anything thats in the air and water. They are also very sensitive to light & heat conditions. If a massive environmental disaster occured that was so devastating that it wiped out thousands of species, including very large robust reptiles like dinosaurs, why did it not wipe out the many frog & reptile populations that have continued pretty much unchanged since that time.

You cant take amphibians alone as counter evidence. There are for example several species of toads and frogs that live in the desert, and lie buried under ground, sometimes for many years, waiting for the conditions to become just right to come to the surface and reproduce.

When food is suddenly very scarce, a huge dinosaur suddenly loses its robustness and starves, while small creatures, or species that can lie dormant for some time (seed bearing plants for instance) gain in robustness...

"Suddenly disappeared..."

[Philippe]

I want to point out that the dinosaurs did not disappear "suddenly", 65MY ago. The decline of dinosaurs began millions of years before that fateful iridium trace in the geological record (aka the cretaceous-tertiary or K-T boundary), and dinosaurs were found in the fossil record on top of that boundary. It's not like they disappeared in one, ten or a hundred years. It took millions of years (tens of thousands of generations) for the dinosaurs to disappear.

Philippe

This is akin to the "Cambrian explosion" theory where at the beginning of the Cambrian, there was suddenly (here's that word again) "exponential" increase in diversity of form (see the Burgess shale for an example). But if you look at it in linear time, and not in compressed (geological) time, the exponential curve looks more and more linear. An explosion that takes hundreds of millions of years to occur is not really an explosion, wouldn't you say?

Re:"Suddenly disappeared..."

[RollingThunder]

As I understand it (from the Science of Diskworld, quite a great read, and about real science despite the title) the problem with the "it was gradual" argument is this.

Fossils are rare. Damn rare to create, even harder to find. Up until Jurassic Park came out, there were all of THREE T-Rex fossils found. They've since found more.

This means that you may find only four or five fossils of a given species. The last one you -happen- to find may be a million years before the K-T boundary, but that's only because you haven't found any newer ones yet.

What is significant, though, is that there is a time when 99.99% of the fossils stop appearing past. There's also evidence of massive dieoffs in the area of the crater of much more common things - I think ammonites were the significant ones, but I don't have the book handy.

Now, this is all thirdhand data (studies, paraphrased by the book, [mis]remembered by me). But it does help explain why you may seem to see species slowly drifting off, when they really all stuck around until that fateful year.

Crater Size Calculator

[T-Punkt]

Well, that's funny. Just this morning I found this link:

http://www.lpl.arizona.edu/tekton/crater.html

Which let's you calculate the estimated diameter of the crater a body of a given size, given density, given speed and given impact angle will make on different targets. (Or reverse that and estimate the diameter of a body that creates a crater of a given size).

Accoring to this a 10km body with the density 3t/m, speed of 25km/sec (=90000 km/h) will create a crater with a diameter of ~216km when it hits Earth in an area of "compent rock or saturated soil" (target density 3t/m).

Re:Yellow journalism

[jc42]

If this were the only evidence, you'd be right. When the impact hypothesis was first fielded, most scientists just said "Interesting; where's your evidence?" But over a couple of decades, geologists and paleontologists have done lots and lots of testing on strata around the world of that age. They keep turning up more and more data that is "consistent with" the impact hypothesis, and nothing that convincingly debunks it. By now, the evidence is overwhelming, so what was a weak hypothesis has elevated to a mostly-accepted theory.

Nowadays, if the face of so much consistent evidence, you'd have to have some really spectacular counter-evidence to be taken seriously. There are still scientists out there trying to debunk the idea, of course, but mostly they just keep turning up more evidence in favor of the impact. That's what this story was. One more of a chain of hundreds of findings that support the general idea of a major impact 65 million years ago.

Has anyone found strata anywhere that is well-dated and continuous across the 65-million-year age that doesn't show a thin anomalous layer and a radical change of fossils?

(Yes, there are continuous strata of around that age that can't be firmly dated. There are also strata that straddle the date but can't be shown to be continuous. None of these is evidence pro or con the impact.)

What does it have to do with nerd news? Well one thing that a few people have been pushing is funding for equipment and people to do a thorough study and census of small objects in the solar system. There could be such an object aimed to hit us Real Soon Now. We don't know. The sooner we can spot such things, the sooner we can do something to deflect them. If we don't, well, one of them will hit the Earth eventually. Maybe it'll hit next week; maybe it'll hit 30 million years from now.

There are roughly a thousand objects now known of km-size or greater that cross the Earth's orbit. None of the known objects will hit the Earth within a century or so. But we have no idea how many more may be out there.

We nerds are just the ones to find them. And knowledge of earlier disasters is one of the best ways to pry funding out of governments agencies.

Re:Yellow journalism

[Joe Decker]

Have some crater pix. Of course these aren't surface artifacts, those would have worn away in the intervening hundreds of millions of years... but the rock densities live on.

I call this direct evidence. Your mileage may vary.

Re:What you say?

[Alien54]

Or did the mice rebuild it? Basically, more or less, yes. Considering that the Impact was 65,000,000 years ago. Plus, evolution is faster when you have a clean slate to play with.

This actually was a big thing a few years ago. Thus you have goodies like the Sky and Telescope Impact Hazards website, along with this nifty cosmic impact calulator.

To be fair, there is this article about a scientist that thinks mass extinctions are a myth. ( I am skeptical of this.

And not that a ten mile wide asteroid would make a mess, but that an asteroid needed to wipe out and actually destroy the earth would likely be much much large, maybe 1,000 miles across or more.

10 miles across is like a bug on the windshield. Note that humans are living on the outside of the windshield.

So it sounds like you get to have fun researching impact craters on google, etc.