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

"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: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: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: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.