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
The Future and Its Enemies The Future and Its Enemies The Future and Its Enemies: The Growing Conflict Over Creativity, Enterprise, and Progress is a 1998 book by Virginia Postrel where she describes the growing conflict in post-Cold War society between "dynamism" – marked by constant change, creativity and exploration in the pursuit of progress – and "stasism", where progress is controlled by careful and cautious planning. Postrel endorses the former, illustrates the differences between the two, and argues that dynamism should be embraced rather than feared. Richard Ebeling wrote a positive review for the Future of Freedom Foundation in May 1999. He remarked, Dr.