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

gulf of mexico

[Anonymous Coward]

Didn't anyone besides me think that this is why the gulf of mexico exists?

Re:gulf of mexico

[jc42]

Well, yeah; probably lots of people would guess at such a hypothesis. But it's not consistent with what is known about the 65-Million-year-old crater on the coast of Yucutan. You'd expect the crater to be near the middle of the Gulf, but it's not. And the crater itself is only maybe 1/10 the diameter f the Gulf.

Also, any geologist will probably tell you that the Gulf of Mexico is much older than that. It's really a very old feature of that part of the planet.

But this shouldn't be taken as a criticism of the idea. The scientific process isn't harmed by such wild guesses. They are often the start of interesting findings. The Gulf of Mexico does look like a "circular feature". It could be an impact crater. But apparently it isn't.

For that matter, the Pacific Ocian is also roughly circular. There has been lots of hypothesizing about this, including the idea that it's the scar left from when the moon was torn from the Earth by the impact of another planet. The scientific jury is still out on this one. After 4.5 billion years, there's not a whole lot of fossil evidence left ...

Re:gulf of mexico

[jc42]

That's part of the problem.

Of course, in many scientific circles, "fossil" is routinely used to refer to any distinct objects or materials found in rocks. The term doesn't just mean remains of once-living organisms. Thus one reads of bits of "fossil gases" entrapped in cracks or bubbles in rocks or ice; these are used to learn about ancient atmospheric conditions. Sedimentary strata contain "fossil rock" as tiny inclusions. And so on.

But still, 4.5 billion years ago, the Earth didn't have much in the way of solid crust, and most of that has long-since been subducted and melted. So we may never have many details from back then. This makes it a bit difficult to find data for or against the "colliding planets" hypothesis. The best argument so far isn't fossil at all. It comes from physicists' attempts to explain how a pair of planets so closely matched as the Earth and its moon can end up in the orbits that we see today. Orbital mechanics seem to preclude this, except as the outcome of a grazing collision between two planet-sized objects.

As a separate subject, though, geologists do say that even if this collision happened, it probably has little if anything to do with the formation of the Pacific Ocean. From what has been learned of plate tectonics in the past decades, it seems that oceans and continents have come and gone many times. The presence of such a large, circular ocean at this time is somewhat of an accident, and wasn't really true at several times in the past billion years.

Gotta go ...

Re:gulf of mexico

[fjordboy]

the whole thing reminds me of a bbc article from about 2 days ago about that mars "fossil" that was found a couple years back. A team of scientists determined that there was no fossils in the rock, it was just magnetite crystals. Sort of interesting, the whole article is located here at bbc.co.uk

Re:gulf of mexico

[Mr. Slippery]

A team of scientists determined that there was no fossils in the rock, it was just magnetite crystals.

"Determined" is much too strong a word. The nature of the magnetic grains has been disputed from the start, and the question is still very much open.

Yellow journalism

[tercero]

I used to have this book that speculated what would happen to the earth if that big of an asteroid hit. One of the things mentioned was a colossal crater (as in more than 1000mi in dia.) that so far is no where visible on Earth.

So they say they found a bunch of bones that suggest "major disturbances in climate that led to the death of most trees and flowering plants." Why does that sort of stuff always lead toward an asteroid that there is no _direct_ evidence of?

This is what I call yellow journalism. It is there opinions and beliefs that are reported and taken as truth.

News flash: It's good for you health to eat saturated fatty foods. The large fat globules travel through the blood vessels and break up smaller globs stuck to the insides of vessels.

BTW: What does this have to do with nerd news? Are there some archeological nerds out there that go to /. for their news?

Re:Yellow journalism

[Mannerism]

Actually, the evidence for the asteroid is pretty compelling IMO. There's a good article about it here.

Re:Yellow journalism

[rudedog]

Umm, why exactly do you think that they keep mentioning the Yucatan Peninsula? It's because that is where they found the Chicxulub crater, mostly covered with water and estimated to be at least 100 miles across. I would bet any money that this book you had was one of those creation "science" books, right?

Re:Yellow journalism

[rve]

Thing with craters on the earth's surface is that they weather. Water, wind, ice, chemicals and life erode the features.

As a result, a crater on earth doesn't look like one on for example Mars: a hole, with a ring around it and an elevation in the middle. The crater on Yukatan for instance, is completely covered with sediment, and can only be recognised with detailed geological research.

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.

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...

Re:Everything but the frogs

[Anonymous Coward]

Frogs are not fragile. Consider that they survive just fine in subarctic Canada as well as the desert.

When it starts getting cold and/or dry, they hibernate. They bury themselves and basically shut down completely until warmth/water returns. They can survive for years in that state. Ditto for salamanders.

If anything, the prevalence of hibernating reptilians and amphibians today is good evidence for mass extinction via asteroid strike.

Re:Everything but the frogs

[fobbman]

Unlikely. They were actually pets of Keith Richards.

Re:Everything but the frogs

[Anonymous DWord]

Pets? I didn't think he was THAT old. I mean, he looks that old, but...

"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..."

[jc42]

Actually, dinosaurs didn't all disappear. At least six species survived, according to recent DNA studies. By whatever coincidence, they were all in the suborder that we call "birds".

The hypothesis that birds are dinosaurs was actually proposed early in the 1800's. The reaction of lots of scientists was the usual "That's an intriguing idea; where's your evidence?" It took more than a century for people to stumble onto convincing evidence. Most of the best evidence has been found in the last 30 years or so. Birds don't fossilize too well. Also, it seems that most of the few good bird fossils are in China, and political problems prevented much serious paleontological work there for a long time.

Also, it wasn't just frogs and salamanders that survived. Several species of mammals managed to hang on until things got better. This included a small tree-shrew-like proto-primate.

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: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.

Old news!

[sofar]

Well, it was 65 million years ago people!

Seriously, this has been accepted widely already in geology. I as a geology student was pleasantly surprised about 4 years ago when my teacher Dr. Jan Smit from the Free University of Amsterdam (a sedimentologist) gave us an introduction in the extinction of the dinosaurs. And even then this was already not *the latest*.

For the non-geologists: J. Smit discovered after some fieldwork and years of research all around the world measuring the K-T boundary (the boundary of strata of where the creteaucious rocks and the tertiary rocks have contact, which is, of course at 65 million years age), that at the Yucatan peninsula there has been an impact crater with a huge diameter (~240km). From this crater ejecta had travelled as far as the great plains...

The story posted here is just one of *many* researches going on right now to verify this theory.

The major point being discussed now is not why did the dinosaurs die, but how did they die when the asteroid hit. The most discussion goes about nuclear winters and climate changes, or even thermal heating due to infall of debris (think 'big eruption'), because it has not really been identified how long the period of extinction was. (at least, as far as I know, comment, anyone?)

I guess the world has some time to accept this story as true, funny how a sometimes dusty science area as geology can already be ahead of the media by far.

Math BS

[melquiades]

But if you look at it in linear time, and not in compressed (geological) time, the exponential curve looks more and more linear.

That doesn't make any sense at all. If you compress time linearly, it's still an exponential curve, no matter how flat it looks. (Any differentiable function locally resembles a line, but that doesn't mean it's linear.)

The whole point of geological time is that evolution happens very slowly by the standard of a human lifetime. The Cambrian explosion was, in fact, pretty fast. You expected, maybe, something like the New Kids on the Block Explosion?

!@#^$% math abuse...

Until real evidence show up...

[Anonymous Coward]

I still stand by my 'invisibly thin line stretched between two trees' theory...

Re:What you say?

[Alien54]

10k wide, 90,000 km/hour
kinetic energy = 1/2 * m * v^2 ,br> mass (kg), velocity(m/s), energy(joules)
Asteroid Otawara is 5.5 k across and has an estimated mass of .2*10^15 kg
1/2 * 200,000,000,000,000 * (90,000 * 3600)^2 =10,497,600,000,000,000,000,000,000,000,000 joules This is the equivalent of 166,628,571,428,571,000 Hiroshima bombs. Thats a big mess :(

hmmmmm, I think there may be a mis calculation

According to the Impact Calculator, based on your initial parameters.

Projectile = Iron Asteroid
Diameter = 10.0 kilometer(s)
Velocity = 25.0 km/s
Target = Earth

Yeilds these results:

Energy Released = 305 million MT (MegaTons of TNT)
(The Dinosaur Killer: 100 million MT)
QUAKE!! Magnitude 11.3 (largest recorded Earthquake: 9.5)
Crater Diameter: 209.0 km
Crater Depth: 1.5 km
A collision this large occurs roughly once every 240 million years.

[insert picture of Marivin the Martian here]

http://janus.astro.umd.edu/gifdir/marvin.jpg

Ohh! Look at all the dust in Earth's atmosphere! It's going to block the sunlight and make it very very cold there for many years. There will be another wave of mass extinctions. You humans will not survive.

Rubber reality cheque: support for many ideas

[leonbrooks]

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.

Unfortunately, the evidence is consistent with a lot of things, including a strong episode of vulcanism, most of what Immanuel Velikovsky's had to say, and the idea of rapid worldwide flooding which so neatly explains many other things (-: a theory so popular on bone-dry Mars, but anathema here on our own soggy globe :-).

What seems to be happening is the same thing, over and over, as when geologist Harlan Bretz fought tooth and nail for four decades before geology accepted his theory for the Spokane badlands. A theory becomes dogma (generally without much real proof) and then all new evidence is seen as conforming to the dogma until finally the explanations become so stretched as to become indefensible, then everyone hurries to been seen as having allowed for the new idea in their old prognostications.

There are a couple of big showstoppers for the meteor-strike-kills-dinosaur idea, including the observation that a lot of dinosaurs did not perish at the end of the Cretaceous, and a lot of creatures which should logically have perished as readily, didn't. Perhaps the most damning is the occasional multiple or conspicuously absent Ir layer, features which are often masked, overlooked or rationalised away during reporting. [pro multi strike] [ con vulcanism] [con flood, many references esp in the linked PDF] [con egg-stinction, but he's wrong, eg non-stealthy birds survived]

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?

I recommend using names, rather than specific ages, or you'll see still more debate about the length of the periods involved, rather than a focus on more ``core'' ideas like seqences of events. And yes, many such have been found; there are less than 200 sites worldwide that do show Ir anomalies, and many of those either show multiple anomalies, or anomalies at depths other than the top of the Cretaceous. Do your own searching. (-:

250,000+ species, millions of tonnes of fossils

[leonbrooks]

...and that was a decade or so ago.

Up until Jurassic Park came out, there were all of THREE T-Rex fossils found.

I think you'll find that this was three complete Rex skeletons, which is quite a different matter.

Flying species like the bird, Archeopteryx, or delicate species like jellyfish don't meet the conditions for fossilisation as easily, so there are only a handful of those. Marine creatures like trilobites and turtles, on the other hand, we have running out of our ears - so in a way Terry Pratchett's Discworld model is actually right, it's turtles at least some of the way down. (-:

Re:We need an ASTEROID defense system not MISSILE!

[Moonshadow]

We already have one! Just take anyone that's ever played "Missle Command" and put them in charge of our nukes.

On the other hand, maybe that's NOT such a great idea.