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Law Of Superposition
The law of superposition is an axiom that forms one of the bases of the sciences of geology, archaeology, and other fields pertaining to geological stratigraphy. In its plainest form, it states that in undeformed stratigraphic sequences, the oldest strata will lie at the bottom of the sequence, while newer material stacks upon the surface to form new deposits over time. This is paramount to stratigraphic dating, which requires a set of assumptions, including that the law of superposition holds true and that an object cannot be older than the materials of which it is composed. To illustrate the practical applications of superposition in scientific inquiry, sedimentary rock that has not been deformed by more than 90° will exhibit the oldest layers on the bottom, thus enabling paleontologists and paleobotanists to identify the relative ages of any fossils found within the strata, with the remains of the most archaic lifeforms confined to the lowest. These findings can inform t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaeological Record
The archaeological record is the body of physical (not written) evidence about the past. It is one of the core concepts in archaeology, the academic discipline concerned with documenting and interpreting the archaeological record. Archaeological theory is used to interpret the archaeological record for a better understanding of human cultures. The archaeological record can consist of the earliest ancient findings as well as contemporary artifacts. Human activity has had a large impact on the archaeological record. Destructive human processes, such as agriculture and land development, may damage or destroy potential archaeological sites. Other threats to the archaeological record include natural phenomena and scavenging. Archaeology can be a destructive science for the finite resources of the archaeological record are lost to excavation. Therefore, archaeologists limit the amount of excavation that they do at each site and keep meticulous records of what is found. The archaeological ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dating Methods
Chronological dating, or simply dating, is the process of attributing to an object or event a date in the past, allowing such object or event to be located in a previously established chronology. This usually requires what is commonly known as a "dating method". Several dating methods exist, depending on different criteria and techniques, and some very well known examples of disciplines using such techniques are, for example, history, archaeology, geology, paleontology, astronomy and even forensic science, since in the latter it is sometimes necessary to investigate the moment in the past during which the death of a cadaver occurred. These methods are typically identified as absolute, which involves a specified date or date range, or relative, which refers to dating which places artifacts or events on a timeline relative to other events and/or artifacts. Other markers can help place an artifact or event in a chronology, such as nearby writings and stratigraphic markers. Absolute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Structural Geology
Structural geology is the study of the three-dimensional distribution of rock units with respect to their deformational histories. The primary goal of structural geology is to use measurements of present-day rock geometries to uncover information about the history of deformation ( strain) in the rocks, and ultimately, to understand the stress field that resulted in the observed strain and geometries. This understanding of the dynamics of the stress field can be linked to important events in the geologic past; a common goal is to understand the structural evolution of a particular area with respect to regionally widespread patterns of rock deformation (e.g., mountain building, rifting) due to plate tectonics. Use and importance The study of geologic structures has been of prime importance in economic geology, both petroleum geology and mining geology. Folded and faulted rock strata commonly form traps that accumulate and concentrate fluids such as petroleum and natural gas. Sim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratigraphy
Stratigraphy is a branch of geology concerned with the study of rock layers ( strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostratigraphy (lithologic stratigraphy), biostratigraphy (biologic stratigraphy), and chronostratigraphy (stratigraphy by age). Historical development Catholic priest Nicholas Steno established the theoretical basis for stratigraphy when he introduced the law of superposition, the principle of original horizontality and the principle of lateral continuity in a 1669 work on the fossilization of organic remains in layers of sediment. The first practical large-scale application of stratigraphy was by William Smith in the 1790s and early 19th century. Known as the "Father of English geology", Smith recognized the significance of strata or rock layering and the importance of fossil markers for correlating strata; he created the first geol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratification (archeology)
Stratigraphy is a key concept to modern archaeological theory and practice. Modern excavation techniques are based on stratigraphic principles. The concept derives from the geological use of the idea that sedimentation takes place according to uniform principles. When archaeological finds are below the surface of the ground (as is most commonly the case), the identification of the context of each find is vital in enabling the archaeologist to draw conclusions about the site and about the nature and date of its occupation. It is the archaeologist's role to attempt to discover what contexts exist and how they came to be created. Archaeological stratification or sequence is the dynamic superimposition of single units of stratigraphy, or contexts. Contexts are single events or actions that leave discrete, detectable traces in the archaeological sequence or stratigraphy. They can be deposits (such as the back-fill of a ditch), structures (such as walls), or "zero thickness surfaci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Principle Of Original Horizontality
The principle of original horizontality states that layers of sediment are originally deposited horizontally under the action of gravity. It is a relative dating technique. The principle is important to the analysis of folded and tilted strata. It was first proposed by the Danish geological pioneer Nicholas Steno (1638–1686). From these observations is derived the conclusion that the Earth has not been static and that great forces have been at work over long periods of time, further leading to the conclusions of the science of plate tectonics; that movement and collisions of large plates of the Earth's crust is the cause of folded strata. As one of Steno's Laws, the principle of original horizontality served well in the nascent days of geological science.Kardel, Troels, ed. (2013). Nicolaus Steno: Biography and Original Papers of a 17th Century Scientist. Berlin: Springer. ISBN 978-3-642-25078-1. However, it is now known that not all sedimentary layers are deposited purely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Principle Of Lateral Continuity
The principle of lateral continuity states that layers of sediment initially extend laterally in all directions; in other words, they are laterally continuous. As a result, rocks that are otherwise similar, but are now separated by a valley or other erosional feature, can be assumed to be originally continuous. Layers of sediment do not extend indefinitely; rather, the limits can be recognized and are controlled by the amount and type of sediment available and the size and shape of the sedimentary basin. As long as sediment is transported to an area, it will eventually be deposited. However, as the amount of material lessens away from the source, the layer of that material will become thinner. Often, coarser-grained material can no longer be transported to an area because the transporting medium has insufficient energy to carry it to that location. In its place, the particles that settle from the transporting medium will be finer-grained, and there will be a lateral transition f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Principle Of Faunal Succession
The principle of faunal succession, also known as the law of faunal succession, is based on the observation that sedimentary rock strata contain fossilized flora and fauna, and that these fossils succeed each other vertically in a specific, reliable order that can be identified over wide horizontal distances. A fossilized Neanderthal bone will never be found in the same stratum as a fossilized Megalosaurus, for example, because neanderthals and megalosaurs lived during different geological periods, separated by many millions of years. This allows for strata to be identified and dated by the fossils found within. This principle, which received its name from the English geologist William Smith, is of great importance in determining the relative age of rocks and strata. The fossil content of rocks together with the law of superposition helps to determine the time sequence in which sedimentary rocks were laid down. Evolution explains the observed faunal and floral succession ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Principle Of Cross-cutting Relationships
Cross-cutting relationships is a principle of geology that states that the geologic feature which cuts another is the younger of the two features. It is a relative dating technique in geology. It was first developed by Danish geological pioneer Nicholas Steno in ''Dissertationis prodromus'' (1669) and later formulated by James Hutton in '' Theory of the Earth'' (1795) and embellished upon by Charles Lyell in '' Principles of Geology'' (1830). Types There are several basic types of cross-cutting relationships: *Structural relationships may be faults or fractures cutting through an older rock. *Intrusional relationships occur when an igneous pluton or dike is intruded into pre-existing rocks. *Stratigraphic relationships may be an erosional surface (or unconformity) cuts across older rock layers, geological structures, or other geological features. *Sedimentological relationships occur where currents have eroded or scoured older sediment in a local area to produce, for examp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harris Matrix
The Harris matrix is a tool used to depict the temporal succession of archaeological contexts and thus the sequence of depositions and surfaces on a 'dry land' archaeological site, otherwise called a 'stratigraphic sequence'. The matrix reflects the relative position and stratigraphic contacts of observable stratigraphic units, or contexts. The Matrix was developed in 1973 in Winchester, England, by Dr. Edward C. Harris. The concept of creating seriation diagrams of archaeological strata based on the physical relationship between strata had had some currency in Winchester and other urban centres in England prior to Harris's formalisation. One of the results of Harris's work, however, was the realisation that sites had to be excavated stratigraphically, in the reverse order to that in which they were created, without the use of arbitrary measures of stratification such as spits or . In his ''Principles of archaeological stratigraphy'' Harris first proposed the need for each u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sequence (archaeological)
In archaeology, seriation is a Relative dating#Archaeology, relative dating method in which assemblage (archaeology), assemblages or artifact (archaeology), artifacts from numerous sites in the same culture are placed in chronological order. Where absolute dating methods, such as radio carbon, cannot be applied, archaeologists have to use relative dating methods to date archaeological finds and features. Seriation is a standard method of dating in archaeology. It can be used to date stone tools, pottery fragments, and other artifacts. In Europe, it has been used frequently to reconstruct the chronological sequence of graves in a cemetery (e.g. Jørgensen 1992; Müssemeier, Nieveler et al. 2003). Contextual and frequency seriation Two different variants of seriation have been applied: contextual seriation and frequency seriation (Renfrew and Bahn 1996, pp. 116–117). Whereas contextual seriation is based on the presence or absence of a Style (visual arts)#Style in arch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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