QZ qz thoughts
a blog from Eli the Bearded

T-Rex and the Crater of Doom

T-Rex and the Crater of Doom
by Walter Alvarez

Walter Alvarez at wikipedia

Walter Alvarez (born October 3, 1940) is a professor in the Earth and Planetary Science department at the University of California, Berkeley. He is most widely known for the theory that dinosaurs were killed by an asteroid impact, developed in collaboration with his father, Nobel Prize winning physicist Luis Alvarez.

A couple of months ago I saw a recommendation for the Crater of Doom book, but I can't recall where. The selling point that worked for me is that it's a very readable book about the history of the theory that an impact caused the death of the dinosaurs. (And many other things at the end of the Cretaceous.)

I found the first person style grating at first, but then I either got used to it, or it improved. The book covers his first inklings of a theory developed in the late seventies until, a couple of years after the discovery of a suitable impact crater on Earth, the Shoemaker–Levy comet hit Jupiter.

Besides the process of formulating a theory from the confusing evidence the various scientists involved had, the book covers how the science of geology has evolved from this process. When geologists believed the world was around 6000 years old, the massive damage seen from shifted rock layers led to "catastrophism" theories to explain this damage. Upon a shift to believing the world to be much, much older (but before knowing how old), geologists switched to "gradualism" which held that except for the very start of the world, things moved slowly.

Plate tectonics was the major shake-up before Chicxulub, initially resisted by geologists until it was shown to also be a gradual change, and then more widely accepted. But gradualists didn't want to consider that the Cretaceous might have ended in a day, and instead countered with theories that put it as a 0.5 to 3 million-year event. The Deccan Traps were created by volcanic action over about that long at about that time in history.

With a crater found at Chicxulub, the ejected debris and evidence of materials shifted by a massive tsunami all layered neatly around it, and all precisely after the Cretaceous layers and before the Tertiary layers, gradualists had to recognize that there were still some catastrophic events impacting (pun unintended) the world.

The book is about 150 pages of main text, and another 50 of notes, most of the notes here are academic citations not asides about the text. A quick read that I found very informative.

6 parts iridium per billion out of 8.

An aside of my own: Chicxulub is pronounced cheek-shoe-lube, so "Chicxulub Crater" makes me think of that passphase generation method presented in (xkcd "correct horse battery staple", a passphrase I find myself unable to remember, in contrast to the last sentence of the comic). And the description of what the immediate effects of the impact would have been like remind me of several xkcd "What if" exercises, such as the first with the near light-speed baseball.

Final thought: has much different passphrase generation methods