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Encyclopedia > Law of superposition

See here for the superposition principle of physics. In linear algebra, the principle of superposition states that, for a linear system, a linear combination of solutions to the system is also a solution to the same linear system. ...


The law of superposition (or the principle of superposition) is an axiom that forms one of the bases of the sciences of geology, archaeology, and other fields dealing with stratigraphy. In its plainest form, that is: layers are arranged in a time sequence, with the oldest on the bottom and the youngest on the top, unless later processes disturb this arrangement. The law was first proposed in the 17th century by the Danish scientist Nicolas Steno. This article includes a list of works cited but its sources remain unclear because it lacks in-text citations. ... Archaeology, archeology, or archæology (from Greek: αρχαίος, archae, ancient; and λόγος, logos, knowledge) is the study of human cultures through the recovery, documentation and analysis of material remains and environmental data, including architecture, artifacts, biofacts, human remains, and landscapes. ... Stratigraphy, a branch of geology, studies rock layers and layering (stratification). ... (16th century - 17th century - 18th century - more centuries) As a means of recording the passage of time, the 17th century was that century which lasted from 1601-1700. ... Nicolaus Steno. ...

Contents

Development of the Law of Superposition

Assuming that all rocks and minerals had once been fluid, Steno reasoned that rock strata were formed when particles in a fluid such as water fell to the bottom. This process would leave horizontal layers. Thus Steno's principle of original horizontality states that rock layers form in the horizontal position, and any deviations from this horizontal position are due to the rocks being disturbed later. Proposed by Nicholas Steno. ...


There are exceptions to this case, because sediments may be deposited on slopes or gradients. These may be steep, locally, and can be up to several degrees. Nevertheless, the principle is essentially true.


Steno stated another, more general principle in this way:

If a solid body is enclosed on all sides by another solid body, of the two bodies that one first became hard which, in the mutual contact, expresses on its own surface the properties of the other surface.

In other words: a solid object will cause any solids that form around it later to conform to its own shape.


Steno was able to show by this reasoning that fossils and crystals must have solidified before the host rock that contains them was formed. If a "tongue stone" had grown within a rock, it would have been distorted by the surrounding rock, in much the same way that a tree root is distorted by growing into a crack in the earth. Instead, the "tongue stone" must have been buried in soft sediments which hardened later. Veins (mineral-filled cracks) and many crystals, on the other hand, must have formed after the surrounding rock was a solid, because they often did show irregularities of form caused by having to conform to the surrounding solid rock. In geology, a vein is a finite volume within a rock, having a distinct shape, filled with mono or poly mineralic crystal aggregates, which were precipitated from an (aqueous) fluid. ...


Finally, in the case of strata, layers on top of a set of strata conform to the shape of lower layers. . . and therefore, in a set of strata, the youngest layers must be those of the top layer, and the oldest must lie on the bottom.


From Steno's observation that rock strata form when particles fall out of suspension in a fluid, it then follows that the youngest stratum is on the top of a sequence. However, this principle also applies to other types of rocks that do not form with water, such as volcanic rocks which spread on older flows, by flow banding. This article or section is in need of attention from an expert on the subject. ... Ignimbrite is a deposit of a pyroclastic flow. ... Flow banding is a geological term to describe bands or layers that can sometimes be seen in rock that formed from the substance molten rock or magma. ...


Steno realized that other geological processes could create apparent exceptions to his laws of superposition and horizontality . He reasoned that the formation of caves might remove part of a lower layer, and that the collapse of a cave might transport large pieces of an upper layer downwards. He recognized that rocks might be uplifted by subterranean forces. Geologists now recognize that tilting, folding, and faulting may also complicate the analysis of a stratigraphic sequence. Molten rock may force its way through surrounding rocks and may sometimes squeeze between older rock layers, also forming an exception to Steno's law. However, such anomalies leave physical evidence in the disturbed rocks; for example, faulted rock layers may be cracked, broken, or metamorphosed along the fault lines. Very tight folds. ... Geologic faults, fault lines or simply faults are planar rock fractures, which show evidence of relative movement. ... Magma is molten rock located beneath the surface of the Earth (or any other terrestrial planet), and which often collects in a magma chamber. ... Metamorphism can be defined as the mineralogical, chemical and crystallographic changes in a solid-state rock, i. ...


Steno's law is a statement of relative time, not absolute time: two rock layers, in principle, could form millions of years apart, or days apart.


Application of the law of superposition

Steno himself saw no difficulty in attributing the formation of most rocks to the flood mentioned in the Bible. However, he noticed that, of the two major rock types in the Apennine Mountains near Florence, Italy, the lower layers had no fossils, while the upper ones were rich in fossils. He suggested that the upper layers had formed in the flood, after the creation of life, while the lower ones had formed before life had existed. This was the first use of geology to try to distinguish different time periods in the Earth's history – an approach that would develop spectacularly in the work of later scientists. The Deluge by Gustave Doré. The story of a Great Flood sent by a deity or deities to destroy civilization as an act of divine retribution is a widespread theme in Greek and many other cultural myths. ... The Apennine Mountains (Greek: Απεννινος; Latin: Appenninus--in both cases used in the singular; Italian: Appennini) is a mountain range stretching 1000 km from the north to the south of Italy along its east coast, traversing the entire peninsula, and forming, as it were, the backbone of the country. ... FOSSIL is a standard for allowing serial communication for telecommunications programs under DOS. FOSSIL is an acronym for Fido Opus Seadog Standard Interface Layer. ... The planet Earth, photographed in the year 1972. ...


The Law of Superposition is widely used in creation science to refute geological scientific arguments on the age of the Earth[citation needed], especially by reference to catastrophism forming turbidites (considered to be evidence of the Great Biblical Flood), which often show exceptions to simplistic applications of the Law of Superposition, specifically the typical conception of a fining up sequence. However, Steno did not recognise fining up sequences, and the Law of Superposition has, (as all scientific laws have), been modified to take into account modern conceptions and increased knowledge of the natural world. Advocates of Creation science lay claim to the methods and empirical practices of science, that is, the scientific method, to assert that scientific evidence supports a literal interpretation of the Biblical account of creation (see Creation according to Genesis). ... A color image of Earth as seen from Apollo 17. ... Catastrophism is the theory that Earth has been affected by sudden, short-lived, violent events that were sometimes worldwide in scope. ... USGS image Turbidite geological formations have their origins in turbidity current deposits, deposits from a form of underwater avalanche that are responsible for distributing vast amounts of clastic sediment into the deep ocean. ...


Thrust faults were also unknown to Steno and his contemporaries and were not described until the late 19th Century and early 20th century by Peach and Horne at Knockan Crag, Scotland, on the Moine Thrust Fault. Thrust faults can cause confusion with the Law of Superposition because they occur parallel to bedding and can be difficult to detect, thus creating situations where inexplicably, older strata can overlay younger. Creation science often uses examples of thrust-faulted stratigraphic sections to disprove the ubiquitous applicability of the Law of Superposition[citation needed]. A thrust fault is a particular type of fault, or break in the fabric of the Earths crust with resulting movement of each side against the other, in which one side is pushed up relative to the other and somewhat over it. ... Motto (Latin) No one provokes me with impunity Cha togar mfhearg gun dioladh (Scottish Gaelic)1 Wha daur meddle wi me?(Scots)1 Anthem (Multiple unofficial anthems) Scotlands location in Europe Capital Edinburgh Largest city Glasgow Official languages English, Gaelic, Scots Government Constitutional monarchy  -  Queen Queen Elizabeth II... The Moine Thrust is not a single thrust but a formation called a thrust belt. ...


One further interesting argument proposed by creation scientists is the unconformable chronostratigraphy and repeated chronostratigraphic sections of the Arctic ice sheet and glaciers of Iceland as evidence of catastrophism and violation of Steno's Law of Superposition.[citation needed] Such features may, in fact, be a thrust fault hosted within the glacial pile. This is of great importance to stratigraphic dating, which assumes that the law of superposition holds true and that an object cannot be older than the materials of which it is composed.


When combined with the related principle of faunal succession, the law of superposition provides a very powerful tool for dating rocks and strata. This article or section does not cite its references or sources. ... The rocky side of a mountain creek near Orosí, Costa Rica. ... For other uses, see strata (novel) and strata title. ...


Superposition as modified by archaeological considerations

Superposition in Archaeology and especially in stratification use during excavation is slightly different as the processes involved in laying down archaeological strata are somewhat different from geological processes. Man made intrusions and activity in the archaeological record need not form chronologically from top to bottom or be deformed from the horizontal as natural strata are by equivalent processes. Some archaeological strata (often termed as contexts or layers) are created by undercutting previous strata. An example would be that the silt backfill of an underground drain would form some time after the ground immediately above it. Other examples of non vertical superposition would be modifications to standing structures such as the creation of new doors and windows in a wall. Superposition in archaeology requires a degree of interpretation to correctly identify chronological sequences and in this sense superposition in archaeology is more dynamic and multi- dimensional. Stratification gooberini went to lousville to dance on a praire and then he went down the hill to hang out with jarry. ... The term archaeological excavation has a double meaning. ... In archaeology, not only the context (physical location) of a discovery a significant fact but the formation of the context is as well. ... Archaeology, archeology, or archæology (from Greek: αρχαίος, archae, ancient; and λόγος, logos, knowledge) is the study of human cultures through the recovery, documentation and analysis of material remains and environmental data, including architecture, artifacts, biofacts, human remains, and landscapes. ... The archaeological sequence or sequence for short, on a specific archaeological site can be defined on two levels of rigour. ...


See also

Proposed by Nicholas Steno. ... The principle of lateral continuity states that layers of sediment initially extend laterally in all directions; in other words, they are laterally continuous. ... There are very few or no other articles that link to this one. ... This article or section does not cite its references or sources. ... Stratigraphy, a branch of geology, studies rock layers and layering (stratification). ... Structural geology is the study of the three dimensional distribution of rock bodies and their planar or folded surfaces, and their internal fabrics. ... The Harris Matrix or Harris-Winchester Matrix is a method of recording and interpreting archaeological sites. ... In archaeology, especially in the course of excavation, stratification is of major interest and significance. ...

References

  • Hamblin, W.K. The Earth's Dynamic Systems, A Textbook in Physical Geology, by W. Kenneth Hamblin, BYU, Provo, UT, Illus. William L. Chesser, Dennis Tasa, (Burgess Publishing Company, Minneapolis, Minnesota), c 1978, pg. 115, "The Principle of Superposition and Original Horizontality;" pg. 116: The Principle of Faunal Succession, "The Principle of Crosscutting Relations;" pg 116-17: "The Principle of Inclusion," (as in the Steno discussion above).
  • Principles of Archaeological Stratigraphy. 40 figs. 1 pl. 136 pp. London & New York: Academic Press. ISBN 0-12-326650-5

  Results from FactBites:
 
Law of superposition - Wikipedia, the free encyclopedia (164 words)
The law of superposition is an axiom that forms one of the bases of the sciences of geology, archaeology, and other fields dealing with geological stratigraphy.
This is of great importance to stratigraphic dating, which assumes that the law of superposition holds true and that an object cannot be older than the materials of which it is composed.
The law was first proposed in the 17th century by the Danish scientist Nicolas Steno.
Rock Ages - Utah Geological Survey (867 words)
Superposition: The most basic concept used in relative dating is the law of superposition.
This law follows two basic assumptions: (1) the beds were originally deposited near horizontal, and (2) the beds were not overturned after their deposition.
Faunal Succession: Similar to the law of superposition is the law of faunal succession, which states that groups of fossil animals and plants occur throughout the geologic record in a distinct and identifiable order.
  More results at FactBites »

 
 

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