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Although joints can occur singly, they most frequently appear as joint sets and systems. A joint set is a family of parallel, evenly spaced joints that can be identified through mapping and analysis of their orientations, spacing, and physical properties. A joint system consists of two or more intersecting joint sets. [1] [2] [3]
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 ...
Structural geology is a critical part of engineering geology, which is concerned with the physical and mechanical properties of natural rocks. Structural fabrics and defects such as faults, folds, foliations and joints are internal weaknesses of rocks which may affect the stability of human engineered structures such as dams , road cuts, open ...
The article currently has four examples of columnar cooling joints (I just removed a fifth) and only one of tectonic joints in sedimentary rocks. Cooling joints are relatively uncommon and are only found in lavas and high-level intrusions, whereas tectonic joints are found in all rock types (including lavas and intrusions).
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.
Systematic Joints are joint systems in which all the joints are parallel or subparallel, and maintain roughly the same spacing from each other. Columnar Joints are joints that cut the formation vertically in (typically) hexagonal columns. These tend to be a result of cooling and contraction in hypabyssal intrusions or lava flows.
In geology and geomorphology, a tessellated pavement is a relatively flat rock surface that is subdivided into polygons by fractures, frequently systematic joints, within the rock. This type of rock pavement bears this name because it is fractured into polygonal blocks that resemble tiles of a mosaic floor, or tessellations. [1]