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Closely related to intercalated contacts is interfingering (also known as intertonguing, [7] interdigitating, or interlocking [8]) of laterally adjacent sedimentary rock bodies. Here the contact breaks down into a series of wedges or tongues that penetrate the adjacent rock body and pinch out individually.
In geology, interbedding occurs when beds (layers of rock) of a particular lithology lie between or alternate with beds of a different lithology. [1] For example, sedimentary rocks may be interbedded if there were sea level variations in their sedimentary depositional environment .
They also observe that there is evidence of diapirism (the intrusion of deformable Cleveland Shale upward into the more brittle Bedford Formation), as well as intertonguing. [57] Baird et al. note that the Cleveland Shale also tilts downward to the south. They suggest that this caused overstepping, rather than intertonguing. [7]
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 ...
Cross-cutting relationships can be used to determine the relative ages of rock strata and other structures. Explanations: A – folded rock strata cut by a thrust fault; B – large intrusion (cutting through A); C – erosional angular unconformity (cutting off A & B) on which rock strata were deposited; D – volcanic dike (cutting through A, B & C); E – even younger rock strata (overlying ...
The earliest references to strata now referred to as Jordan were made by many of the pioneering geologists of the upper Midwest. In an 1852 report on the geology of Wisconsin, Iowa, and Minnesota, D. D. Owen assigned it to the uppermost part of his “Lower Sandstone” (the “Upper Sandstone” referring to what is now called the St. Peter). [8]
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, an igneous intrusion (or intrusive body [1] or simply intrusion [2]) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth.