Abundance of the chemical elements in the Sun and outer planets is similar to that in the universe. Due to solar heating, the elements of Earth and the inner rocky planets of the Solar System have undergone an additional depletion of volatile hydrogen, helium, neon, nitrogen, and carbon (which volatilizes as methane). The crust, mantle, and core of the Earth show evidence of chemical segregation plus some sequestration by density. Lighter silicates of aluminum are found in the crust, with more magnesium silicate in the mantle, while metallic iron and nickel compose the core. The abundance of elements in specialized environments, such as atmospheres, or
Earth-Two the "Dark Flash") entered the mainstream DC Universe and threatened to destroy it. These alternate realities are usually addressed as "Elsewhere" and "Elseworld" stories. Kal-L, Lois Lane-Kent, Superboy-Prime, and Alexander Luthor returned during "Infinite Crisis". Unknown to Kal-L, Luthor's plan was to resurrect the pre-"Crisis" Multiverse. He wanted to mix and match elements from each reality to create a "perfect world". The fallout of the conflict brought the short-lived return of an Earth-Two copy and the deaths of Kal-L, Lois Lane-Kent and Luthor Jr. of Earth-Two. It is unclear what happened to the aged Diana Trevor, the Earth-Two Wonder Woman,