There’s a massive lump of liquidized, carbon-rich material hiding hundreds of kilometers beneath Yellowstone’s supervolcano and the greater Western United States area. It’s truly massive – 1.8 million square kilometers (about 700,000 square miles) in size – and it’s bubbling inside the upper region of the mantle, the region of the planet that’s a partly-molten churning mass of fiery doom.
https://www.iflscience.com/seriously...lowstone-40363