When did we first begin to suspect that the Earth had an Iron Catastrophe?

Question

I've searched, and found some interesting articles on the subject such as the Wikipedia article, which is a nice summary. But most of the references in these articles are to other popular culture articles/documentaries on the subject. I can't actually find any details on the original research and geologists who proposed the idea and when/where the first evidence that this event took place was unearthed (obviously the magnetic field is a glaring piece of that evidence) and how it was eventually interpreted to come to this conclusion.

I would have thought that the first significant propositions for this would have perhaps come around the beginning of the 20th century... maybe....

Answer 1

I would have thought that the first significant propositions for this would have perhaps come around the beginning of the 20th century, maybe.

I would think it was quite a bit later. Victor Goldschmidt published his classification of elements as siderophile, chalcophile, lithophile, or atmophile in the late 1920s. This marked the beginning of modern geochemistry, and I would put the date well after this.

Geologists of the 19th and early 20th century were very skeptical of "contributions" to geology by the physical sciences. Physicists and astronomers in the late 19th century thought the Earth was no more than a few tens of millions years old. Geologists knew it had to be much older than that. Geology, physics, and astronomy wouldn't agree on an age of the Earth until the mid 1950s.

One problem with the concept of an iron catastrophe is that it was a catastrophic event. Geologists had spent a good chunk of the 19th century overturning biblical-based geology in favor of uniformitarianism (or gradualism). By the late 19th century / early 20th century, a biblical, catastrophic view of geology was deemed non-scientific. There were no catastrophes. (As an aside, this was one of the key drivers in geology's rejection of Alfred Wegener's theory of continental drift.) It wasn't until the 1960s that the theory of plate tectonics took hold.

It wasn't until the 1960s were when geologists seriously started considering catastrophic events such as the formation of the Earth's core. There were some predecessors, and these can be found as references to 1960 era articles. Francis Birch investigated the energy released by the formation of the Earth's core in his 1965 publication "Energetics of core formation," Journal of Geophysical Research 70.24:6217-6221. He references earlier material, the earliest of which is Kuhn and Rittmann, "Über den Zustand des Erdinnern und seine Entstehung aus einem homogenen Urzustand", Geol. Rundschau 32, 215-256, 1941 (translated title: "About the state of the Earth's interior and its origination from a homogeneous original state").

I don't know whether Kuhn and Rittmann investigated the energetic consequences of the formation of the Earth's core in 1941. Birch most definitely did do so in 1965.