The Glossary has expanded coverage particularly in such active fields as carbonate sedimentology, environmental geology and geophysics, GIS, GPS, hydrology and hydraulics, marine and coastal geology, organic geochemistry, paleoecology, seismology, stratigraphic nomenclature, speleology and karst, and structural geology and tectonics. Many definitions provide a syllabification guide and background information. Thus a reader will learn the difference between look-alike pairs, such as sylvanite (a mineral) and sylvinite (a rock); the origin of terms; the meaning of abbreviations and acronyms common in the geosciences vocabulary; the dates many terms were first used; the meaning of certain prefixes; and the preferred term of two or more synonyms. The authority of this edition, like that of its predecessors, rests on the expertise of geoscientists from many specialties, who have reviewed definitions, added new terms, and cited references. Their contributions make the Glossary an essential reference work for all in the geosciences community.