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In geology, a dike or dyke is a sheet of rock that is formed in a fracture of a pre-existing rock body. Dikes can be either magmatic or sedimentary in origin. Magmatic dikes form when magma flows into a crack then solidifies as a sheet intrusion , either cutting across layers of rock or through a contiguous mass of rock.
Terminology varies regionally. When used as field boundaries, dry stone structures are more commonly known as dykes in Scotland, where professional dry stone wall builders are referred to as 'dykers'. Dry stone walls are characteristic of upland areas of Britain and Ireland where rock outcrops naturally or large stones exist in quantity in the ...
A clastic dike is a seam of sedimentary material that fills an open fracture in and cuts across sedimentary rock strata or layering in other rock types. Clastic dikes form rapidly by fluidized injection (mobilization of pressurized pore fluids) or passively by water, wind, and gravity (sediment swept into open cracks).
A sheeted dyke complex, or sheeted dike complex, is a series of sub-parallel intrusions of igneous rock, forming a layer within the oceanic crust. [1] At mid-ocean ridges , dykes are formed when magma beneath areas of tectonic plate divergence travels through a fracture in the earlier formed oceanic crust, feeding the lavas above and cooling ...
Thus the magma, intruded between existing rocks, solidifies into large thin sheets of igneous rock. They are among the most extensive igneous features on Earth, [citation needed] in the form of dikes, laccoliths, cone sheets and sills. When limestone or other precipitate forms in a fault space, it is a sedimentary sheet intrusion.
Heavy construction equipment is usually used due to the amounts of material to be moved — up to millions of cubic metres. Earthwork construction was revolutionized by the development of the scraper and other earth-moving machines such as the loader, the dump truck, the grader, the bulldozer, the backhoe, and the dragline excavator.
Diabase (/ ˈ d aɪ. ə ˌ b eɪ s /), also called dolerite (/ ˈ d ɒ l. ə ˌ r aɪ t /) or microgabbro, [1] is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grained to aphanitic chilled margins which may ...
Sills are fed by dikes, [3] except in unusual locations where they form in nearly vertical beds attached directly to a magma source. The rocks must be brittle and fracture to create the planes along which the magma intrudes the parent rock bodies, whether this occurs along preexisting planes between sedimentary or volcanic beds or weakened planes related to foliation in metamorphic rock.