Encyclopedia of Global Resources part 56 provides a wide variety of perspectives on both traditional and more recent views of Earth's resources. It serves as a bridge connecting the domains of resource exploitation, environmentalism, geology, and biology, and it explains their interrelationships in terms that students and other nonspecialists can understand. The articles in this set are extremely diverse, with articles covering soil, fisheries, forests, aluminum, the Industrial Revolution, the . Department of the Interior, the hydrologic cycle, glass, and placer mineral deposits. . | 498 Geographic information systems Global Resources hydration of the gel and subsequent crystallization occur along with shrinkage and cracking of the geode wall allowing mineral-bearing waters to percolate into the geode and deposit cr ystals on the cavity wall. Subsequent periods of water circulation and crystallization may follow forming the characteristic layers of cr ystals. Geodes are found in many parts of the world. One well-known type found in Uruguay is called hydrolite or water stone because it contains quartz crystals left when water containing silica in solution evaporated. Many highly prized geodes that are filled with beautiful crystals and curved-banded colors of agate can be found at various collecting sites in the United States such as near Dugway Utah and Keokuk Iowa. Alvin K. Benson See also Groundwater Hydrothermal solutions and mineralization Limestone Quartz Sedimentary processes rocks and mineral deposits Silicates. Geographic information systems Category Scientific disciplines Geographic information systems GIS originated primarily from efforts to manage natural resources and analyze environmental issues. In recent years advances in computing technology and the development of large digital databases have made GIS a powerful tool for analyzing the natural environment. GIS is particularly suited to support multidisciplinar y analyses of natural systems at a variety of scales. Background Although geographic information systems GIS scientists and practitioners may define GIS in broader terms the initials are commonly used to refer to the computer software and peripheral technologies that are used to collect manipulate analyze and visualize geographic information. While many of the concepts that underpin GIS have a long history in academic disciplines such as cartography geography and planning GIS computer software largely originated in the 1960 s with academic and government initiatives to study how computers could be used to make maps and .
