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A joint system consists of two or more intersecting joint sets. [1] [2] [3] The distinction between joints and faults hinges on the terms visible or measurable, a difference that depends on the scale of observation. Faults differ from joints in that they exhibit visible or measurable lateral movement between the opposite surfaces of the ...
Columnar jointing in Giant's Causeway in Northern Ireland Columnar jointing in the Alcantara Gorge, Sicily. Columnar jointing is a geological structure where sets of intersecting closely spaced fractures, referred to as joints, result in the formation of a regular array of polygonal prisms (basalt prisms), or columns.
In metamorphic geology, a compatibility diagram shows how the mineral assemblage of a metamorphic rock in thermodynamic equilibrium varies with composition at a fixed temperature and pressure. Compatibility diagrams provide an excellent way to analyze how variations in the rock's composition affect the mineral paragenesis that develops in a ...
A discontinuity may exist as a single feature (e.g. fault, isolated joint or fracture) and in some circumstances, a discontinuity is treated as a single discontinuity although it belongs to a discontinuity set, in particular if the spacing is very wide compared to the size of the engineering application or to the size of the geotechnical unit.
In geology and geophysics, thermal subsidence is a mechanism of subsidence in which conductive cooling of the mantle thickens the lithosphere and causes it to decrease in elevation. This is because of thermal expansion : as mantle material cools and becomes part of the mechanically rigid lithosphere, it becomes denser than the surrounding material.
Igneous rock – Rock formed through the cooling and solidification of magma or lava; Metamorphic rock – Rock that was subjected to heat and pressure; Sedimentary rock – Rock formed by the deposition and cementation of particles; Structural geology – Science of the description and interpretation of deformation in the Earth's crust
Earth's crust ranges from 5 to 70 kilometres (3.1–43.5 mi) [7] in depth and is the outermost layer. [8] The thin parts are the oceanic crust , which underlies the ocean basins (5–10 km) and is mafic -rich [ 9 ] (dense iron-magnesium silicate mineral or igneous rock ). [ 10 ]
There are a number of different specialized magnetic compasses used by geologists to measure orientation of geological structures, as they map in the field, to analyze and document the geometry of bedding planes, joints, and/or metamorphic foliations and lineations. [1] [2] In this aspect the most common device used to date is the analogue compass.