CanadaPlus , 15 days ago (edited 15 days ago)

Uh, I’ll find one, and edit. It confused the shit out of Victorian scientists, because they had a good guess how old the Earth is from biology, and had thermodynamics, but it was telling them volcanism shouldn’t still be happening.

Edit:

Wikipedia mentions it in the geothermal article, but the source is a textbook, and who has time and/or money for that? There’s also the article on the age of the Earth. Ah, here we go, in the article on Earth’s internal heat budget. Somebody also linked a paper on it elsewhere in this thread.

These give slightly different numbers from each other, but the gist is that radioisotopes (Uranium, Thorium and Potassium being the primordial ones) account for at least half.