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Encyclopedia of Global Resources part 115

Encyclopedia of Global Resources part 115 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 U.S. Department of the Interior, the hydrologic cycle, glass, and placer mineral deposits. . | 1068 Sedimentary processes rocks and mineral deposits Global Resources Sedimentary processes rocks and mineral deposits Categories Geological processes and formations mineral and other nonliving resources Sedimentary processes occur only at the Earth s surface because they are driven by various components of the hydrologic and biologic cycles. Sedimentar y processes involve the breakdown movement and ultimate deposition of broken rock fragments and chemicals in solution. These processes create many of the important resources used by humans. Background Most sediments originate from the weathering of existing rocks. Weathering is the breakdown of earth material by physical and or chemical processes. Physical weathering only breaks the original material into smaller sizes. This is accomplished through mechanical means such as freezing and thawing plant-root wedging differential heating of rocks and cr ystal growth in rock cracks. Chemical weathering on the other hand actually changes the composition of the original material into completely different components through solution oxidation hydration and or hydrolysis. The by-products of physical and chemical weathering provide the different types of sediment and ion-bearing solutions that create sedimentar y rocks and minerals. Biological activity can also create sediments. Many invertebrates and some algae utilize calcium carbonate in seawater to make shells. Organisms such as coral live in warm shallow seas and construct reefs. In addition both macro- and microscopic shells of organisms that do not live in reef communities become sediments that blanket the seafloor after the organisms deaths. Also some algae and bacteria as well as swamp vegetation can become organic sediments under certain conditions of oxygen deficiency creating valuable fossil fuels. Transportation Once particles of rock are loosened and broken free by weathering processes those particles can be carried off by water wind or glaciers. Ions released .