Iridium and Catastrophes...

One of my side projects required the use of the wonderful element called iridium. (It's fiction, but I do wish I was working in a lab with it, indeed with any of the platinides!) I had a vague recollection of Jaki mentioning it in some unusual context, and finally located it. (The context, not the iridium. If you know where to get some, please let me know. I'd just want a sample.)

As if by supreme irony, the first major evidence of global geological catastrophes was spotted within a few years of the centenary of the publication of the Origin [of Species]. In 1967, the Nobel-laureate physicist, W. Alwarez and his associates, who included his son, L. Alwarez, began to test their theory about periodic geological upheavals, through a field work in the precipitous mountainsides rising above the Italian town of Gubbio. There they found at the K-T boundary, that separates the Cretaceous from the Tertiary period, a pencil-thin layer very rich in iridium. Since iridium is very rare on earth but very abundant in meteors, it appeared logical to place the source of iridium, that was later found elsewhere on the globe in the same layer, in the earth's collision with an asteroid ten kilometers or so in diameter.
While the idea created at first considerable controversy, it is now generally conceded that among the factors that brought about the end of the Cretaceous period and the extinction of the dinosaurs (among other things), there was one collision with a huge body from outer space. The cataclysm triggered thereby is best given in the words of the younger Alvarez:

In the first days after the earth was hit, dust blanketed the entire world. It grew pitch-dark from one to three months. If the impact was on land, it probably got bitter cold. If it hit at sea, the water vapor could have created a greenhouse effect, making things hot. Hot nitric acid would have rained out of the atmosphere life-threatening rain that would have dissolved the shells of organisms.

This apocalyptic scenario has become even more so with further details emerging from the analysis of the iridium from that layer. Associated with that iridium were large amounts of soot which can only be explained if much of the earth was enveloped in fire. According to E. Anders, a cosmochemist at the University of Chicago,

even if it [the asteroid] hit in the ocean, the impact would have created a crater 300 kilometers across. A huge plume would have pushed the atmosphere aside. The fireball would have had a radius of several thousand kilometers. Winds of hundreds of kilometers an hour would have swept the planet for hours, drying trees like a giant hair dryer. Two-thousand-degree rock vapor would have spread rapidly. It would have condensed to white-hot grains that could have started additional fires.

The feverish research in historical biology sparked by the discovery of Alvarez has now completely discredited the idea of a slowly changing geological past. Instead, we have not only a geological past pockmarked with global catastrophes, but also a biological past riddled with extinctions of life-forms on a giant scale and at a periodic rate, roughly 26 million years.
[SLJ The Purpose of It All, 53-55]

One of the very curious harmonies between Jaki and Chesterton occurs here. The Father Brown story called "The Strange Crime of John Boulnois" (ca. 1914), begins with the mention of

a very unobtrusive Oxford man named John Boulnois wrote in a very unreadable review called The Natural Philosophic Quarterly a series of articles on alleged weak points in Darwinian evolution, it fluttered no corner of the English papers; though Boulnois's theory (which was that of a comparatively stationary universe visited occasionally by convulsions of change) had some rather faddy fashionableness at Oxford, and got so far as to be named "Catastrophism."
[GKC The Wisdom of Father Brown]

I don't know if any historian of science has done a study of the real-world theory, but it would be interesting to find out if Chesterton has the priority. Given some of the known error-correcting strategies in the DNA replication system it seems that Boulnois (and Chesterton) might be far closer to reality than Darwin... but I make no claim here. The matter (even if partially tongue-in-cheek) is left for further research. But the iridium seems to speak for itself.