07 January 2009

Dinosaur Extinction:  After the Impact?

"The age of the dinosaurs ended 65 million years ago with a gigantic asteroid. No one knows precisely when or where the next asteroid will strike. Could humans be the next species to face extinction?" (From the Science Channel website)

On the Science Channel 2 July 2007 there was a docu-drama called "Super Comet: After the Impact" (the latest in the super disaster films, the previous being "Supervolcano"). It follows four groups of people in different places (Mexico, Hawaii, France, and Camaroon) trying to survive a comet of similar size as the one that impacted 65 million years ago hitting in pretty much the same place. What are the odds of that? I don't know but it can't be very likely, but for sake of edutainment let's assume this comet hit in the very same spot the last one did. There were a few bits of outdated science that were presented, and some continuity problems which I will present as follows.

1. The impact is said to have created a megatsunami 3000 feet tall after impacting the ocean near the Chicxulub peninsula, resulting in massive inland flooding around the world. However, about 40 minutes later when a satelite image is shown of the region, the crater is entirely on land. It was a land-based impact and therefore could not have created a megatsunami.

2. The film tells us that ejecta from the impact (debris shot out of the crater and into space) will rain down on the earth and raise temperatures to 600 degrees F, enough to ignite all flamable material on the surface of the planet. We know this is not true. The Chicxulub impact 65 million years ago was believed to have let do world-wide forest fires because a layer of ash was found all over the world's surface, however ash can be blown by the wind thousands of kilometers, and we know the huge impact created very fast winds. Charcoal, which cannot be blown far by the wind, was not found world-wide, meaning there were no forestfires consuming all flamable material on the planet. There would have been fires endemic to the region of impact but there could not have been fires all over the globe. There's just no evidence of it. If a similar sized object impacted the earth it would have to be made of napalm in order to turn the world into one big fire.

3. The impact is said to hit a region of carbonate rock, which combined with the water vapour in the atmosphere would produce sulfuric acid rain (H2SO4). This, too, is wrong. How do we know? Well, there's no evidence of it happening when the previous Chicxulub impact took place. If you'll remember your days from science class you'll recall that when sulfuric acid was poured into the container of sugar it turned into a giant black thing. Well if we are to believe battery acid fell from the sky it would have killed vunerable amphibians living in the shallow waters. And that's precicely what we don't see! The amphibians didn't go extinct when the dinosaurs did, even though they were more succeptable to the battery acid rain! In fact amphibians thrived following the impact since there were no giant lizzards roaming around eating everything.

So what? No megatsunami, no world-wide forest fires, no battery acid rain. What next? Well, did an impact really kill off the dinosaurs? The evidence is starting to look shakey. Prof. Gerta Keller of Princeton University and Prof. Wolfgang Stinnesbeck of the University of Karlsruhe have come up with some compelling evidence to toss aside the theory of a single large impact killing off the dinosaurs. Fossil records show a gradual extinction happening over millions of years. Furthermore, cores drilled from the Gulf of Mexico show that the Chicxulub impact happened 300,000 years BEFORE the dinosaurs went extinct.

Well, what did kill the dinosaurs? I'm getting there. 500,000 years before the K-T boundary, and 200,000 years before the impact, massive volcanic activity began in India. A flood basalt eruption produced millions of cubic kilometers of new rock over hundreds of thousands of years and created the Deccan Traps.

This massive volcanic activity exerted pressure on the biosphere and caused the gradual downfall of the dinosaurs and other Cretaceous creatures. The Chicxulub impact was just one of a long line of hits the earth took during this time period. It is believed a second impact (the K-T impact), larger than the one at Chicxulub, was the final straw that pushed the dinosaurs over the edge and produced the tell-tale iridum layer. The exact location of this second impact (which it will be called here until someone comes up with a better name than the K-T impact) has yet to be discovered, but tentative evidence points to somewhere in the Indian Ocean.

Next time will the producers of mega-disaster docu-dramas insert more science and less Jerry Bruckheimer? I don't know, but hopefully an equilibrium will be reached when "Super Sun Spot: Day of Reckoning" comes out.