Hell on Earth 65 Million Years Ago

The wildfires that consumed much of the American West during the summer of 1988 have been a disaster, but they are nothing compared with a much greater fire that may have happened 65 million years ago.

That age, which is when the dinosaurs disappeared, has become a familiar topic of scientific discussion in recent years. Many scientists have speculated about the possibility that a dramatic catastrophe from outer space was the cause of the dinosaurs’ extinction.

In the rocky layers that were laid down about 65 million years ago, there is a surprisingly large quantity of the rare metal iridium. Iridium is very rare in the Earth’s crust, but it is more common in meteorites and comets. This 65-million-year-old iridium layer has been found wherever scientists have looked, so the supposition is that a large asteroid or comet struck the Earth 65 million years ago, and killed off most of the living species on Earth, including the dinosaurs.

Why were they killed all over the Earth, if the asteroid hit only in a single place? The first answer was that the asteroid kicked up a huge cloud of powdered rock, soil and dust that spread throughout the upper atmosphere and blocked the light of the sun for months. That would have killed most of the world’s plant life and animal life, too, since animals depend on plants for food, directly or indirectly.

If that weren’t enough, a large strike like that was bound to make itself felt in other ways. For instance, 70% of the Earth’s surface is covered by water, so that the asteroid is likely to have splashed into the ocean. It would, of course, penetrate right through to the ocean floor and still kick up the deadly dust that would block the sunlight. It would, however, also splash the water, forming a huge tsunami, often inaccurately termed a tidal wave.

The asteroid, however, may have had an even worse effect. Recently, Edward Anders of the University of Chicago and other researchers reported on that key layer of rock laid down 65 million years ago in places as diverse as Switzerland, Denmark and New Zealand. Wherever they looked, they found a layer of soot, anywhere from 100 to 10,000 times as concentrated as seemed reasonable to expect.

This soot seemed most likely to have been the remains of a fire, and by studying the exact nature of the soot, the quantity of carbon present and the proportion of different atomic varieties (or “isotopes”) it contained, the geologists came to the conclusion that it was all one fire, taking place at one time, something that was global in nature.

Here is the scenario: The huge inrushing object from outer space must have punctured the Earth’s crust and, in addition, in order to send up a vast cloud of dust and walls of water, also must have allowed the heated rock (magma) beneath the crust to spew upward. The magma may have arisen both at the site of the primary puncture and elsewhere on Earth as the strike cracked and shoved the Earth’s crustal plates.

Enormous volcanic activity would have set fires in many different places at the same time and all may have joined in a roaring, worldwide conflagration.

There is also the possibility that enough carbon dioxide was produced to bring about a warming trend through the greenhouse effect. Nitrogen oxides might have been produced that would have resulted in a vast period of acid rain. Carbon monoxide and various other small carbon-containing compounds must have been formed that poisoned the atmosphere for a while.

It’s a dreadful picture and I wonder if it can be entirely correct. I can’t help but see it as a kind of overkill. What with dust in the upper atmosphere, walls of water, continental firestorms, carbon dioxide, acid rain, poisons of all sort, the catastrophic scenario is simply too much. If it all happened 65 million years ago, then, of course that’s what killed the dinosaurs. The question then becomes, how could any life survive?