Encyclopaedia Of Geology

Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates. In modern times, geology is commercially important for mineral and hydrocarbon exploration and for evaluating water resources; it is publicly important for the prediction and understanding of natural hazards, the remediation of environmental problems, and for providing insights into past climate change; plays a role in geotechnical engineering; and is a major academic discipline. The majority of geological data come from research on solid Earth materials. These typically fall into one of two categories: rock and unconsolidated material. In the 1960s, a series of discoveries, the most important of which was seafloor spreading, showed that the Earth's lithosphere, which includes the crust and rigid uppermost portion of the upper mantle, is separated into a number of tectonic plates that move across the plastically deforming, solid, upper mantle, which is called the asthenosphere. There is an intimate coupling between the movement of the plates on the surface and the convection of the mantle: oceanic plate motions and mantle convection currents always move in the same direction, because the oceanic lithosphere is the rigid upper thermal boundary layer of the convecting mantle. This coupling between rigid plates moving on the surface of the Earth and the convecting mantle is called plate tectonics. The present encyclopaedia is a concise and up-to-date work including all aspects of this subject. Every effort has been made in the representation manner in this encyclopaedia so that the students do not get confused while going through this encyclopaedia.