Crust (geology) enriched compared to the underlying mantle. Although the continental crust comprises only about 0.6 weight percent of the silicate on Earth, it contains 20% to 70% of the incompatible elements. All the other constituents except water occur only in very small quantities and total less than 1%. Estimates of average density for the upper crust range between 2.69 and 2.74 g/cm and for lower crust between 3.0 and 3.25 g/cm. Earth formed approximately 4.6 billion years ago from a disk of dust and gas orbiting the newly formed Sun. It formed via accretion, where planetesimals and other smaller rocky bodies
Faith in the Earth all. The Earth represents our one and only window of opportunity, at the same time as it symbolizes all of our unknown higher potentials. Neither spaceman nor God will come to save us. But this is not a bleak dystopian materialism, because just as our simian ancestors couldn't realize that the development of their vocal cords (something they already had at least in rudimentary form) would open up those new dimensions of reality that we call language, civilization, and culture, just so we ourselves cannot yet get our minds around what we might be able to do already in rudimentary