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
Return to the Centre of the Earth the Orquesta Sinfónica de Tenerife, but the difficulties in performing around such an ecological area led to the idea being scrapped. Material from "Return to the Centre of the Earth" was performed live for the first time as part of Wakeman's 25-date Half a Century Tour, playing a selection of material across his career in churches and cathedrals across the United Kingdom from May 1999. A tour of the album, complete with a stage set designed by Dean, was shelved. Wakeman has performed the album live in its entirety twice, both times in Québec, Canada. The premiere took place on