Tales From The Travels

The popular theory is that a massive meteor struck the Earth 65 million years ago near what is now known as Chicxulub, Mexico. The effects of this impact destroyed the environment and caused the extinction of about 85% of the world’s lifeforms in what is known as the Cretaceous-Tertiary, or K-T, extinction.

The evidence that a large impact occurred is conclusive. It is also clear that this impact caused widespread destruction of an unbelievable magnitude. Gigantic tsunamis ringed the world, earthquakes of a severity that we can’t imagine radiated out from the impact, returning debris caused firestorms, the suspended dust in the air caused climate change. And, of course, the impact site itself was totally obliterated with absolutely nothing surviving.

I became aware of this theory over 25 years ago and, at first, was skeptical. I read the comments that geologists and paleontologists made and they argued the evidence did not support the theory. As I continued with my education, I learned more and more about this theory and remained skeptical. I met many of the people that were involved with investigating it and even met Walter Alvarez, who first proposed the theory with his father, physicist Louis Alvarez, and got to talk to these people first hand. I have read a great deal about it and have studied the evidence.

This is one case when the evidence was enough to cause me to change my opinion. Or, at least to stop voicing my opposition. Many times, when I came up with an objection to the theory, the investigators were able to find the necessary evidence to show I was wrong.

One of the principle claims of the theory is that the impact put so much dust in the air that it blocked out the sunlight and caused what is known as a ‘nuclear winter.’ The idea of the nuclear winter has been discredited and found to be wrong. Placing giant amounts of dust in the air will not cause the world to go into massive climate change on the scale that was being proposed. When people pointed at some volcanic eruptions that had caused some climate change, I argued that it wasn’t the dust, it was the sulfur that was the source of the effect. Investigation later showed that the impact area had very large sulfur deposits which would have been put into the atmosphere as an aerosol. I argued this still would not cause a winter lasting for decades, as claimed, but my objections were not as strong.

I argued that the fossil evidence showed that many of the animals that went extinct actually survived the impact by as much as hundreds of thousands of years. Further analysis of those fossil records showed that the fossil beds had been disturbed, possibly even by the impact itself, and this disturbance had relocated the fossils out of the geologic sequence.

On and on it went. I made objections and they were able to counter them. Eventually, I began to accept they might have been right, after all. The answer to all of my objections, I decided, was just still buried and was simply waiting to be discovered. The fact that we didn’t know all of the answers didn’t make the theory invalid. It just meant we had to continue the research.

And yet, I always had a nagging problem with the whole scenario. Some of their claims did not make sense to me under the laws of physics.

One of the greatest problems I have had and continue to have is the description of worldwide firestorms that would, in essence, incinerate everything in the world. Under this scenario, the debris lifted out of the crater would rain back down all over the world with so much energy that it would turn the world into an oven with temperatures as high as thousands of degrees. This, I said, was not possible.

The amount of debris excavated by the impact, when distributed over the entire planet, would be very thin. It is not possible that it could carry enough energy to cause the temperature of the entire planet to skyrocket. But, they were able to show there was a layer of soot that dated to just after the impact. The claim is that this is soot from the worldwide fires. Not so, I said. All this shows is that soot was deposited. The accuracy of the thin sedimentary layer cannot show if that soot was deposited over 1 year or 100 years. It is undeniable that the impact occurred and it would certainly have caused enormous destruction. Certainly, entire forested regions would have been killed by the resulting cataclysm. With all of this dead wood sitting around, it would only be a matter of time before it caught fire. This kind of event would be repeated all over the world, resulting in just such a layer of soot as was observed.

I did some calculations of the amount of energy released by the impact. My estimates came in around 5 x 10^23 joules of energy. The accepted value is that it was probably around 4 x 10^23 joules, so I was very close. This is a truly unbelievable amount of energy. To put this in context, a 100 mega-ton atomic bomb, larger than any ever detonated, would release about 10^17 joules. In other words, the impact released the amount of energy in one million such bombs. This amount of energy is about 50 times as much as the second largest know explosion in history, the La Garita Caldera in Colorado. This was an explosive volcanic event that occurred some time about 26 million years ago and released around 10^22 joules, about 1/50th the size of the Chicxulub impact. This caldera is so large that geologists studied it for decades before they realized what it is.

But, even this extreme amount of energy would not result in the cataclysm that is claimed. Using a radius of the Earth of 6400 kilometers and an atmosphere thickness of 150 kilometers, I find that this would have resulted in about 10^3 joules per cubic meter, on average. This is enough to melt about 10 ice cubes and is far below what would be needed to result in the devastation claimed. Plus, the overwhelming majority of the released energy would have been concentrated in the immediate vicinity. This would have been a very large vicinity measuring many hundreds of miles across, but still small on a global scale. The resulting amount of energy for most of the planet to absorb would have been much less than the average.

So, I have listened to the theories and even teach it in my astronomy class, but there has always been a nagging problem in my mind that it just didn’t fit the laws of physics, at least not the way they were claiming. Now, evidence is starting to mount that the theory might be wrong after all and I read a recent NSF release with great interest. This report tells of how researchers have shown that the impact occurred long before the extinction, maybe as much as 300,000 years before. They have done some very nice research and uncovered some very strong evidence to support their claims. It will be very difficult to explain away what they have produced.

So, it looks like my gut instincts might have been right after all. I believe the impact occurred and that it was devastating. But, I’m skeptical about its role in the K-T extinction. I just don’t think this theory fits the laws of physics. There clearly is more research that needs to be done.