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Lithospheric flexure (also called regional isostasy) is the process by which the Lake Bonneville" US Geological Survey Monograph No. 1
1890. 438 p. The concept was not retaken until the 1950s by Vening Meinesz. The geometry of the lithospheric bending is often modeled adopting a pure elastic thin plate approach (sometimes by fitting the
Lithospheric flexure (also called regional isostasy) is the process by which the lithosphere
A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of up to thousands of years ...
(rigid, thin outer layer of the Earth) bends under the action of forces such as the weight of a growing orogeny
Orogeny is a mountain building process. An orogeny is an event that takes place at a convergent plate margin when plate motion compresses the margin. An ''orogenic belt'' or ''orogen'' develops as the compressed plate crumples and is uplifted ...
or changes in ice thickness related to glaciation
A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...
. The lithosphere rests on the asthenosphere
The asthenosphere () is the mechanically weak and ductile region of the upper mantle of Earth. It lies below the lithosphere, at a depth between ~ below the surface, and extends as deep as . However, the lower boundary of the asthenosphere is ...
, a viscous layer that in geological time scales behaves like a fluid. Thus, when loaded, the lithosphere progressively reaches an isostatic equilibrium, which represents Archimedes' principle
Archimedes' principle (also spelled Archimedes's principle) states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially, is equal to the weight of the fluid that the body displaces. Archimedes' ...
applied to geological settings.
This phenomenon was first described in the late 19th century to explain the shorelines uplifted in Scandinavia
Scandinavia; Sámi languages: /. ( ) is a subregion in Northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. In English usage, ''Scandinavia'' most commonly refers to Denmark, Norway, and Swed ...
by the removal of large ice massed during the last glaciation. G. K. Gilbert used it to explain the uplifted shorelines of Lake Bonneville
Lake Bonneville was the largest Late Pleistocene paleolake in the Great Basin of western North America. It was a pluvial lake that formed in response to an increase in precipitation and a decrease in evaporation as a result of cooler temperature ...
.1890. 438 p. The concept was not retaken until the 1950s by Vening Meinesz. The geometry of the lithospheric bending is often modeled adopting a pure elastic thin plate approach (sometimes by fitting the
gravity anomaly
The gravity anomaly at a location on the Earth's surface is the difference between the observed value of gravity and the value predicted by a theoretical model. If the Earth were an ideal oblate spheroid of uniform density, then the gravity meas ...
produced by that bending rather than more direct data of it). The thickness of such plate that best fits the observed lithospheric bending is called the equivalent elastic thickness of the lithosphere and is related to the stiffness or rigidity of the lithosphere. These lithospheric bending calculations are typically performed following the Euler-Bernoulli bending formulation, or alternatively the Lagrange equation.
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