In geology, a rheid is a solid material that deforms by viscous flow. To be considered a rheid, deformation by flow should exceed elastic deformation by at least a factor of three. Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it. ... A solid is a state of matter, characterized by a definite volume and a definite shape (i. ... Viscosity is a measure of the resistance of a fluid to deformation under shear stress. ... There are separate articles about elasticity in economics, and about British rubber bands. ...

Types of rheids

Almost any type of rock can behave as a rheid under appropriate conditions of temperature and pressure. For example, the Earth's mantle is believed to undergo convection over long time scales. Since the mantle is known to be solid (it supports the propagation of shear waves), it must be behaving as a rheid. Halite, the mineral form of salt, is a geological material that behaves as a rheid over relatively short time periods. As salt is buried by other types of sediments, it will often flow laterally towards regions of less confining stress. Through this mechanism, salt domes and other structures are formed. In some areas, such as the Gulf of Mexico, these structures often serve as traps for petroleum and natural gas. Sedimentary, volcanic, plutonic, metamorphic rock types of North America. ... Temperature is the physical property of a system which underlies the common notions of hot and cold; the material with the higher temperature is said to be hotter. ... Pressure (symbol: p or P) is the measure of the force that acts on a unit area. ... Earth, also known as the Earth or Terra, is the third planet outward from the Sun. ... The mantle is the layer in the structure of the Earth that lies directly under the Earths crust. ... Convection is the transfer of heat by the motion of or within a fluid. ... A seismic wave is a wave that travels through the Earth, often as the result of an earthquake or explosion. ... Halite is the mineral of sodium chloride, NaCl, commonly known as rock salt. ... Sodium chloride, also known as common salt, table salt, or halite, is a chemical compound with formula NaCl. ... Two types of sedimentary rock: limey shale overlaid by limestone. ... Stress tensor In physics, stress is the internal distribution of forces within a body that balance and react to the loads applied to it. ... A salt dome is formed when a thick bed of evaporite minerals (mainly salt, or halite) found at depth intrudes vertically into surrounding rock strata, forming a diapir. ... The Gulf of Mexico is a major body of water bordered and nearly landlocked by North America. ... Nodding donkey pumping an oil well near Sarnia, Ontario, 2001 Petroleum (from Greek petra – rock and oleum – oil), crude oil, sometimes colloquially called black gold, is a thick, dark brown or greenish flammable liquid, which exists in the upper strata of some areas of the Earths crust. ... Natural gas - Wikipedia /**/ @import /skins/monobook/IE50Fixes. ...

See also

• Rheology

Rheology is the study of the deformation and flow of matter. ...

External links

• Definition of rheid (http://geology.dictonarypage.co.uk/rheid/)