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Isostasy (Greek ísos 'equal', stásis 'standstill') or isostatic equilibrium is the state of gravitational equilibrium between Earth's crust (or lithosphere) and mantle such that the crust "floats" at an elevation that depends on its thickness and density.
In geology, the term compression refers to a set of stresses directed toward the center of a rock mass. Compressive strength refers to the maximum amount of compressive stress that can be applied to a material before failure occurs.
However, some of the density increase is compression under the enormous pressures inside the Earth. The effect of pressure can be calculated using the Adams–Williamson equation. The conclusion is that pressure alone cannot account for the increase in density. Instead, we know that the Earth's core is composed of an alloy of iron and other ...
While theory in colloquial usage may denote a hunch or conjecture, a scientific theory is a set of principles that explains an observable phenomenon in natural terms. [127] [128] "Scientific fact and theory are not categorically separable", [129] and evolution is a theory in the same sense as germ theory or the theory of gravitation. [130]
The balance of nature, also known as ecological balance, is a theory that proposes that ecological systems are usually in a stable equilibrium or homeostasis, which is to say that a small change (the size of a particular population, for example) will be corrected by some negative feedback that will bring the parameter back to its original "point of balance" with the rest of the system.
Anderson's theory of faulting, devised by Ernest Masson Anderson in 1905, is a way of classifying geological faults by use of principal stress. [1] [2] A fault is a fracture in the surface of the Earth that occurs when rocks break under extreme stress. [3] Movement of rock along the fracture occurs in faults.
The null point theory has been controversial in its acceptance into mainstream coastal science as the theory operates in dynamic equilibrium or unstable equilibrium, and many fields and laboratory observations have failed to replicate the state of a null point at each grain size throughout the profile. [3]
Slab pull is a geophysical mechanism whereby the cooling and subsequent densifying of a subducting tectonic plate produces a downward force along the rest of the plate. In 1975 Forsyth and Uyeda used the inverse theory method to show that, of the many forces likely to be driving plate motion, slab pull was the strongest. [1]