I might have been wrong about the atmosphere...

Discovering the Universe, 6th Edition. Comings, N & Kaufmann III, W. 2003

Venus' crust is about 300 km thick (Earth's, by comparison, is 65 km thick).

Incorrect statement on my part about the atmosphere heating up the crust. The radioactive elements heat the insulated crust to the point where it melts, and then the pent-up heat escapes and the process starts again.

Inference on my part that the atmosphere plays a part in it. It's still a pressure cooker, as probes and lander have unfortunately found out.

My bad ops: