GEOLOGY Uranus lacks a solid surface; thus, it has no traditional geological features like mountains or valleys. Its structure comprises an icy and rocky core, possibly surrounded by a mantle of icy materials like water, methane, and ammonia. The extreme pressure and temperatures within Uranus might create an interior where water exists as a hot, high-pressure form of ice. This unique composition contributes to its magnetic field generation and might cause unusual phenomena like diamond rain, where carbon might crystallize into diamonds due to immense pressure deep within the planet.