I was asked, so I will infodump about the mountains that were eaten by a hotspot.
First, a few not so stray facts.
It's been known since the mid 1800s that there was a connection between the Oishita mountains of Oklahoma and the Appalachian mountains. Geologically EVERYTHING MATCHED UP! The only problem was about 1200 miles of missing mountains!
Next is hotspots down deep in the Earth's mantle. The mantle is hot enough to be semi liquid. It develops convection currents. Even by geological standards they are slow. However they can bring enormous amounts of heat energy to the crust above it.
Now we get to Pangea, the ancient supercontinent which, in breaking up, gave the plates that became all the modern continents. Pangea had a huge mountain range that ended with a large hook shape.
In modern times, the remains of it begin in Scandinavia, cross Scotland, and become the Appalachian mountains, which used to have the hook of the J shape, ending in modern Oklahoma.
Yes, the whole central American drainage flowed North! Geological traces of that river system and the inland sea it caused are still around.
What happened? Continental drift. The North American Plate drifted across what will become known as the Bermuda Hotspot. It melted the mountains away from underneath.
In some places, the event left traces exactly on the line of the continental drift. They are a series of kimberlite plutons, the most famous of which is the Arkansas Crater of Diamonds.
A pluton is created when the surface melting goes so deep that it reaches the Moho, the boundary between crust and mantle. Unlike other crustal features, a pluton reaches through the entire thickness of the crust.
And that is what happened to about 1200 miles of mountains!
