Describes the chemical composition, or saltiness, of the ocean and discusses the effect of man on the oceans as well as the processes that formed the oceans and now maintain their balance.
Discusses the divisions of time used by geologists to record earth's history and includes information on fossils, radioactive dating, and prehistoric life.
Describes the formation of different types of mountains and metamorphic rock (rocks that change form in the intense heat and pressure of the Earth's interior) and discusses their impact on their environment.
Describes the theory of plate tectonics and the various forces that continue to change the surface of the earth. Discusses the history of the theory as well as evidence that seems to dispute it.