Evolution of the Earth: An Introduction and Overview
Ideas for Earth evolution emerge from our recognition that the process of formation was one that was traumatic and hot but that a large part of the memory of this was lost by rapid subsequent cooling. A memory of this initial condition is nonetheless preserved in the geochemistry of the Earth, including core composition and perhaps thermal state. Some perspectives on the history of the field are offered, particularly on the role of Lord Kelvin and his incorrect estimate of the age of the Earth, and the role of the Soviet school of cosmogony in providing a view of Earth formation that invokes common rather than special processes. Some simple scaling arguments are offered to promote understanding of the timescales and energy budgets that govern Earth formation and evolution. A commentary is provided that links the topics covered in this volume, with emphasis on the interconnected nature of all aspects of Earth evolution, including life. Some outstanding questions are listed and debated.
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