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Systematic joints are planar, parallel, joints that can be traced for some distance, and occur at regularly, evenly spaced distances on the order of centimeters, meters, tens of meters, or even hundreds of meters. As a result, they occur as families of joints that form recognizable joint sets.
Conjugate Joints occur when the joints intersect each other at angles significantly less than ninety degrees. 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 ...
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. Columnar jointing occurs in many types of igneous rocks and forms as the rock cools and contracts.
Tensile stress forms joints in rocks. A joint is a fracture that forms within a rock, whose movement to open the fracture is greater than the lateral movement that takes place. Joints are formed in the direction perpendicular to the least principal stress, meaning that they are formed perpendicular to the tensile stress. [ 1 ]
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 .
In geotechnical engineering, a discontinuity (often referred to as a joint) is a plane or surface that marks a change in physical or chemical characteristics in a soil or rock mass. A discontinuity can be, for example, a bedding , schistosity , foliation , joint , cleavage , fracture , fissure , crack, or fault plane.
Basalt columns seen on Porto Santo Island, Portugal. Columnar jointing of volcanic rocks exists in many places on Earth. Perhaps the most famous basalt lava flow in the world is the Giant's Causeway in Northern Ireland, in which the vertical joints form polygonal columns and give the impression of having been artificially constructed.
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...