Stepping Stones To Change PDF Download

Many people know more about the planets Venus and Mars than they do about our home planet, Earth. Unique in our solar system, and so far as we know in the Universe itself, the Earth has been evolving for the past five billion years, and is the result of the dynamic interplay of astronomical,physical, and chemical forces ranging from the vast to the barely perceptible. The evolution of the Earth has never been predictable. Life has come very close to being extinguished many times. After each such crisis, the survivors and their genes have diversified and grown in number to exploit allopportunities. Without such traumas it is hardly likely that evolution's pace could have reached its present advanced level; that of conscious life capable of changing the world, contemplating it, and in doing so changing itself at geologically stupendous rates. In Stepping Stones, Stephen Druryexplores how such a seemingly fragile world could have been formed and developed. Looking at the astonishing leaps, and near catastrophes that have occurred along the way, intermingled with inexorable but slow change, the book interweaves the evidence from geology, physics, biology, and chemistry,to tell an extraordinary story of the Earth's evolution spanning nearly five billion years.