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 Metropolis police officer who often assisted "Daily Planet" cub reporter Jimmy Olsen and superhero Black Lightning. Many characters would often travel from one Earth to the other and interact with its natives or even immigrate. For example, Larry Jordan, the first Air Wave and native of Earth-Two, traveled to Earth-One under yet-unexplained circumstances, married Helen (the second Air Wave) and raised a son, Hal (the third Air Wave). The history of Earth-Two is slightly different from both real world history and the history of other DC continuities. For example, in classic Earth-Two stories, by the 1970s, Quebec is shown to