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In geology, a bed is a layer of sediment, sedimentary rock, or volcanic rock "bounded above and below by more or less well-defined bedding surfaces". [1] A bedding surface is three-dimensional surface , planar or curved, that visibly separates each successive bed (of the same or different lithology ) from the preceding or following bed.
In geology, a graded bed is a bed characterized by a systematic change in grain or clast size from bottom to top of the bed. Most commonly this takes the form of normal grading, with coarser sediments at the base, which grade upward into progressively finer ones. Such a bed is also described as fining upward. [1]
In geology, cross-bedding, also known as cross-stratification, is layering within a stratum and at an angle to the main bedding plane. The sedimentary structures which result are roughly horizontal units composed of inclined layers.
These structures are within sedimentary bedding and can help with the interpretation of depositional environment and paleocurrent directions. They are formed when the sediment is deposited. Cross-bedding Cross-bedding is the layering of beds deposited by wind or water inclined at an angle as much as 35° from the horizontal. [1]
Primary fabric (bedding) shown by abrupt change in clast size, secondary fabric shown by penetrative S-fabric, cleavage, in fine-grained rock, and by shape fabric in deformed volcanic clasts. Cape Forchu, Nova Scotia. In geology, a rock's fabric describes the spatial and geometric configuration of all the elements that make it up.
Heterolithic bedding is a sedimentary structure made up of interbedded deposits of sand and mud. It is formed mainly in tidal flats but can also be formed in glacial environments. Examples from fluvial environments have been documented but are rare. [ 1 ]
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 ...
Lenticular bedding is a sedimentary bedding pattern displaying alternating layers of mud and sand. Formed during periods of slack water , mud suspended in the water is deposited on top of small formations of sand once the water's velocity has reached zero.