This new encyclopedia from the Facts On File Science Library offers approximately 700 alphabetically arranged entries ranging from one paragraph to a few pages and covering earth science subdisciplines (hydrology, oceanography, and so on) as well as concepts, theories and hypotheses, places, events, geological time periods, history, technology, and key individuals. Many entries have further-reading lists and cross-references. There are hundreds of black-and-white photos, drawings, charts, and maps. The illustrations are generally clear and detailed. Nineteen feature essays are scattered throughout the text. Two appendixes follow the entries, one containing a periodic table of elements, the other displaying a geologic time scale and other information.