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
Geology of the Iberian Peninsula in the study of geology in Spain. In 1972 the MAGNA plan was created to produce 1:50000 scale maps of Spain (this work began in Portugal in 1952). Between 1986 and 1987 a Spanish-French collaboration called ECORS-Pirineos made a seismic vertical reflection profile 250 km long through the Pyrenees. By 2000 there were six seismic profiles through the Pyrenees which provided a wealth of information of the thickness of the crust and the internal structure of the orogen. Between 1852 and 1857, Carlos Ribeiro made a geological map at 1:480 000 scale of the Portuguese region between the Douro and