Guide to materials in geology and earth sciences. Worldwide coverage. Abstracts journal articles, books, maps, conference papers, reports, and theses.Over 25,145 sources. Over 2.1 million records. Over 60,000 records added annually. Geology and the Earth Sciences. Major subjects include: crystallography, hydrogeology, economic geology, hydrology and water resources, environmental geology, marine geology, engineering geology, mineralogy, geochemistry, oceanography, geophysics, and paleontology. From 1785 to the present for North American geologyFrom 1933 to the present for international geo.