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The noble gases make up a class of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low chemical reactivity. The six naturally occurring noble gases are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and the radioactive radon (Rn).
Radiocarbon dating is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon.
Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay products, which form at a known constant rate of decay. The use of radiometric dating was first published in 1907 by Bertram Boltwood and is now the principal source of information about the absolute age of rocks and other geological features, including the age of fossilized life forms or the age of Earth itself, and can also be used to date a wide range of natural and man-made materials.
Carbon-14, C-14, 14
C or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Its presence in organic materials is the basis of the radiocarbon dating method pioneered by Willard Libby and colleagues (1949) to date archaeological, geological and hydrogeological samples. Carbon-14 was discovered on February 27, 1940, by Martin Kamen and Sam Ruben at the University of California Radiation Laboratory in Berkeley, California. Its existence had been suggested by Franz Kurie in 1934.
Diagenesis is the process that describes physical and chemical changes in sediments first caused by water-rock interactions, microbial activity, and compaction after their deposition. Increased pressure and temperature only start to play a role as sediments become buried much deeper in the Earth's crust. In the early stages, the transformation of poorly consolidated sediments into sedimentary rock (lithification) is simply accompanied by a reduction in porosity and water expulsion, while their main mineralogical assemblages remain unaltered. As the rock is carried deeper by further deposition above, its organic content is progressively transformed into kerogens and bitumens. The process of diagenesis excludes surface alteration (weathering) and deep metamorphism. There is no sharp boundary between diagenesis and metamorphism, but the latter occurs at higher temperatures and pressures. Hydrothermal solutions, meteoric groundwater, rock porosity, permeability, dissolution/precipitation reactions, and time are all influential factors.
Isotope analysis is the identification of isotopic signature, abundance of certain stable isotopes of chemical elements within organic and inorganic compounds. Isotopic analysis can be used to understand the flow of energy through a food web, to reconstruct past environmental and climatic conditions, to investigate human and animal diets, for food authentification, and a variety of other physical, geological, palaeontological and chemical processes. Stable isotope ratios are measured using mass spectrometry, which separates the different isotopes of an element on the basis of their mass-to-charge ratio.
Ninhydrin (2,2-dihydroxyindane-1,3-dione) is an organic compound with the formula C6H4(CO)2C(OH)2. It is used to detect ammonia and amines. Upon reaction with these amines, ninhydrin gets converted into deep blue or purple derivatives, which are called Ruhemann's purple. Ninhydrin is most commonly used to detect fingerprints, as the terminal amines of lysine residues in peptides and proteins sloughed off in fingerprints react with ninhydrin.
Geoarchaeology is a multi-disciplinary approach which uses the techniques and subject matter of geography, geology, geophysics and other Earth sciences to examine topics which inform archaeological knowledge and thought. Geoarchaeologists study the natural physical processes that affect archaeological sites such as geomorphology, the formation of sites through geological processes and the effects on buried sites and artifacts post-deposition. Geoarchaeologists' work frequently involves studying soil and sediments as well as other geographical concepts to contribute an archaeological study. Geoarchaeologists may also use computer cartography, geographic information systems (GIS) and digital elevation models (DEM) in combination with disciplines from human and social sciences and earth sciences. Geoarchaeology is important to society because it informs archaeologists about the geomorphology of the soil, sediment, and rocks on the buried sites and artifacts they are researching. By doing this, scientists are able to locate ancient cities and artifacts and estimate by the quality of soil how "prehistoric" they really are. Geoarchaeology is considered a sub-field of environmental archaeology because soil can be altered by human behavior, which archaeologists are then able to study and reconstruct past landscapes and conditions.
The term bioarchaeology has been attributed to British archaeologist Grahame Clark who, in 1972, defined it as the study of animal and human bones from archaeological sites. Redefined in 1977 by Jane Buikstra, bioarchaeology in the United States now refers to the scientific study of human remains from archaeological sites, a discipline known in other countries as osteoarchaeology, osteology or palaeo-osteology. Compared to bioarchaeology, osteoarchaeology is the scientific study that solely focus on the human skeleton. The human skeleton is used to tell us about health, lifestyle, diet, mortality and physique of the past. Furthermore, palaeo-osteology is simple the study of ancient bones.
Obsidian hydration dating (OHD) is a geochemical method of determining age in either absolute or relative terms of an artifact made of obsidian.
Fluorine absorption dating is a method used to determine the amount of time an object has been underground.
Nitrogen trifluoride is an inorganic, colorless, non-flammable, toxic gas with a slightly musty odor. It finds increasing use within the manufacturing of flat-panel displays, photovoltaics, LEDs and other microelectronics. Nitrogen trifluoride is also an extremely strong and long-lived greenhouse gas. Its atmospheric burden exceeded 2 parts per trillion during 2019 and has doubled every five years since the late 20th century.
Absolute dating is the process of determining an age on a specified chronology in archaeology and geology. Some scientists prefer the terms chronometric or calendar dating, as use of the word "absolute" implies an unwarranted certainty of accuracy. Absolute dating provides a numerical age or range, in contrast with relative dating, which places events in order without any measure of the age between events.
Luminescence dating refers to a group of methods of determining how long ago mineral grains were last exposed to sunlight or sufficient heating. It is useful to geologists and archaeologists who want to know when such an event occurred. It uses various methods to stimulate and measure luminescence.
Amino acid dating is a dating technique used to estimate the age of a specimen in paleobiology, molecular paleontology, archaeology, forensic science, taphonomy, sedimentary geology and other fields. This technique relates changes in amino acid molecules to the time elapsed since they were formed.
The Pinza-Abu Cave Man is a prehistoric people known from bones found in the Pinza-Abu Cave, near Ueno in Miyako Island, southern Japan. The remains appear to have the modern man anatomical type and have been dated to about 30,000 years ago, i.e. 25,800 ± 900 and 26,800 ± 1,300 before present. The name "Pinza-Abu" literally means "goat cave" in the local Miyakoan language.
Samples used for radiocarbon dating must be handled carefully to avoid contamination. Not all material can be dated by this method; only samples containing organic matter can be tested: the date found will be the date of death of the plants or animals from which the sample originally came.
The 946 eruption of Paektu Mountain in Korea and China, also known as the Millennium Eruption or Tianchi eruption, was one of the most powerful volcanic eruptions in recorded history and is classified as a VEI-7 event. The eruption resulted in a brief period of significant climate change in Manchuria. The year of the eruption has not been precisely determined, but a possible year is A.D. 946.
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.
Ancient proteins are the ancestors of modern proteins that survive as molecular fossils. Certain structural features of functional importance, particularly relating to metabolism and reproduction, are often conserved through geologic time. Early proteins consisted of simple amino acids, with more complicated amino acids being formed at a later stage through biosynthesis. Such late-arising amino acids included molecules like: histidine, phenylalanine, cysteine, methionine, tryptophan, and tyrosine. Ancient enzymatic proteins performed basic metabolic functions and required the presence of specific co-factors. The characteristics and ages of these proteins can be traced through comparisons of multiple genomes, the distribution of specific architectures, amino acid sequences, and the signatures of specific products caused by particular enzymatic activities. Alpha and beta proteins (α/β) are considered the oldest class of proteins.
References
Lyndsie Krogh Sr. at Stanford University
- 1 2 "Nitrogen dating - Oxford Reference".
{{cite journal}}: Cite journal requires|journal=(help) - 1 2 3 4 Haddy, A.; Hanson, A. (1982-02-01). "Research Notes and Application Reports Nitrogen and Fluorine Dating of Moundville Skeletal Samples" (PDF). Archaeometry. 24 (1): 37–44. doi:10.1111/j.1475-4754.1982.tb00645.x. hdl: 2027.42/65569 . ISSN 1475-4754.
- ↑ Moore, Jim. "Paleoanthropological methods: Dating fossils" (PDF). UCSD.