Hal worked sis years as an engineer for the California Com- pany, and six more years as an engineer in otiierfirms.Using the vast experience he had gained in these assignments for drilling, production and remedial oper- ations, Hal formed a consulting firm (H.W, Addington and Associates)...
Earth's crust was still undergoing significant changes as tectonic plates moved and collided, giving rise to the first continents. These plates also caused Earth's surface to shift and buckle, creating mountains and deep ocean trenches. Early Earth's axis tilted differently than it does now, lea...