1.
Chronology
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Chronology is the science of arranging events in their order of occurrence in time. Consider, for example, the use of a timeline or sequence of events and it is also the determination of the actual temporal sequence of past events. It is also part of the discipline of history, including history, the earth sciences. Chronology is the science of locating historical events in time and it relies upon chronometry, which is also known as timekeeping, and historiography, which examines the writing of history and the use of historical methods. Radiocarbon dating estimates the age of living things by measuring the proportion of carbon-14 isotope in their carbon content. Dendrochronology is used in turn as a reference for radiocarbon dating curves. The familiar terms calendar and era concern two complementary concepts of chronology. Dionysius Exiguus was the founder of that era, which is nowadays the most widespread dating system on earth, an epoch is the date when an era begins. Ab Urbe condita is Latin for from the founding of the City and it was used to identify the Roman year by a few Roman historians. Modern historians use it more frequently than the Romans themselves did. Before the advent of the critical edition of historical Roman works, AUC was indiscriminately added to them by earlier editors. It was used systematically for the first time only about the year 400, pope Boniface IV, in about the year 600, seems to have been the first who made a connection between these this era and Anno Domini. Dionysius Exiguus’ Anno Domini era was extended by Bede to the complete Christian era, while of critical importance to the historian, methods of determining chronology are used in most disciplines of science, especially astronomy, geology, paleontology and archaeology. In the absence of written history, with its chronicles and king lists and this method of dating is known as seriation. Known wares discovered at strata in sometimes quite distant sites, the product of trade, laboratory techniques developed particularly after mid-20th century helped constantly revise and refine the chronologies developed for specific cultural areas. Unrelated dating methods help reinforce a chronology, an axiom of corroborative evidence, ideally, archaeological materials used for dating a site should complement each other and provide a means of cross-checking. Conclusions drawn from just one unsupported technique are usually regarded as unreliable, the fundamental problem of chronology is to synchronize events. By synchronizing an event it becomes possible to relate it to the current time, among historians, a typical need to is to synchronize the reigns of kings and leaders in order to relate the history of one country or region to that of another
2.
Archaeology
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Archaeology, or archeology, is the study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, Archaeology can be considered both a social science and a branch of the humanities. In North America, archaeology is considered a sub-field of anthropology, archaeologists study human prehistory and history, from the development of the first stone tools at Lomekwi in East Africa 3.3 million years ago up until recent decades. Archaeology as a field is distinct from the discipline of palaeontology, Archaeology is particularly important for learning about prehistoric societies, for whom there may be no written records to study. Prehistory includes over 99% of the human past, from the Paleolithic until the advent of literacy in societies across the world, Archaeology has various goals, which range from understanding culture history to reconstructing past lifeways to documenting and explaining changes in human societies through time. The discipline involves surveying, excavation and eventually analysis of data collected to learn more about the past, in broad scope, archaeology relies on cross-disciplinary research. Archaeology developed out of antiquarianism in Europe during the 19th century, Archaeology has been used by nation-states to create particular visions of the past. Nonetheless, today, archaeologists face many problems, such as dealing with pseudoarchaeology, the looting of artifacts, a lack of public interest, the science of archaeology grew out of the older multi-disciplinary study known as antiquarianism. Antiquarians studied history with attention to ancient artifacts and manuscripts. Tentative steps towards the systematization of archaeology as a science took place during the Enlightenment era in Europe in the 17th and 18th centuries, in Europe, philosophical interest in the remains of Greco-Roman civilization and the rediscovery of classical culture began in the late Middle Age. Antiquarians, including John Leland and William Camden, conducted surveys of the English countryside, one of the first sites to undergo archaeological excavation was Stonehenge and other megalithic monuments in England. John Aubrey was a pioneer archaeologist who recorded numerous megalithic and other monuments in southern England. He was also ahead of his time in the analysis of his findings and he attempted to chart the chronological stylistic evolution of handwriting, medieval architecture, costume, and shield-shapes. Excavations were also carried out in the ancient towns of Pompeii and Herculaneum and these excavations began in 1748 in Pompeii, while in Herculaneum they began in 1738. The discovery of entire towns, complete with utensils and even human shapes, however, prior to the development of modern techniques, excavations tended to be haphazard, the importance of concepts such as stratification and context were overlooked. The father of archaeological excavation was William Cunnington and he undertook excavations in Wiltshire from around 1798, funded by Sir Richard Colt Hoare. Cunnington made meticulous recordings of neolithic and Bronze Age barrows, one of the major achievements of 19th century archaeology was the development of stratigraphy. The idea of overlapping strata tracing back to successive periods was borrowed from the new geological and paleontological work of scholars like William Smith, James Hutton, the application of stratigraphy to archaeology first took place with the excavations of prehistorical and Bronze Age sites
3.
Geology
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Geology is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also refer generally to the study of the features of any terrestrial planet. Geology gives insight into the history of the Earth by providing the evidence for plate tectonics, the evolutionary history of life. Geology also plays a role in engineering and is a major academic discipline. The majority of data comes from research on solid Earth materials. These typically fall into one of two categories, rock and unconsolidated material, the majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth. There are three types of rock, igneous, sedimentary, and metamorphic. The rock cycle is an important concept in geology which illustrates the relationships between three types of rock, and magma. When a rock crystallizes from melt, it is an igneous rock, the sedimentary rock can then be subsequently turned into a metamorphic rock due to heat and pressure and is then weathered, eroded, deposited, and lithified, ultimately becoming a sedimentary rock. Sedimentary rock may also be re-eroded and redeposited, and metamorphic rock may also undergo additional metamorphism, all three types of rocks may be re-melted, when this happens, a new magma is formed, from which an igneous rock may once again crystallize. Geologists also study unlithified material which typically comes from more recent deposits and these materials are superficial deposits which lie above the bedrock. Because of this, the study of material is often known as Quaternary geology. This includes the study of sediment and soils, including studies in geomorphology, sedimentology and this theory is supported by several types of observations, including seafloor spreading, and the global distribution of mountain terrain and seismicity. This coupling between rigid plates moving on the surface of the Earth and the mantle is called plate tectonics. The development of plate tectonics provided a basis for many observations of the solid Earth. Long linear regions of geologic features could be explained as plate boundaries, mid-ocean ridges, high regions on the seafloor where hydrothermal vents and volcanoes exist, were explained as divergent boundaries, where two plates move apart. Arcs of volcanoes and earthquakes were explained as convergent boundaries, where one plate subducts under another, transform boundaries, such as the San Andreas Fault system, resulted in widespread powerful earthquakes. Plate tectonics also provided a mechanism for Alfred Wegeners theory of continental drift and they also provided a driving force for crustal deformation, and a new setting for the observations of structural geology
4.
Relative dating
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Relative dating is the science of determining the relative order of past events, without necessarily determining their absolute age. In geology, rock or superficial deposits, fossils and lithologies can be used to correlate one stratigraphic column with another. Prior to the discovery of radiometric dating which provided a means of dating in the early 20th century. Though relative dating can determine the sequential order in which a series of events occurred, not when they occur. Relative dating by biostratigraphy is the method in paleontology, and is in some respects more accurate. The regular order of occurrence of fossils in rock layers was discovered around 1800 by William Smith, while digging the Somerset Coal Canal in southwest England, he found that fossils were always in the same order in the rock layers. As he continued his job as a surveyor, he found the same patterns across England and he also found that certain animals were in only certain layers and that they were in the same layers all across England. Due to that discovery, Smith was able to recognize the order that the rocks were formed, sixteen years after his discovery, he published a geological map of England showing the rocks of different geologic time eras. Methods for relative dating were developed when geology first emerged as a formal science, geologists still use the following principles today as a means to provide information about geologic history and the timing of geologic events. The principle of Uniformitarianism states that the processes observed in operation that modify the Earths crust at present have worked in much the same way over geologic time. A fundamental principle of geology advanced by the 18th century Scottish physician, in Huttons words, the past history of our globe must be explained by what can be seen to be happening now. The principle of intrusive relationships concerns crosscutting intrusions, in geology, when an igneous intrusion cuts across a formation of sedimentary rock, it can be determined that the igneous intrusion is younger than the sedimentary rock. There are a number of different types of intrusions, including stocks, laccoliths, batholiths, sills, the principle of cross-cutting relationships pertains to the formation of faults and the age of the sequences through which they cut. Finding the key bed in these situations may help determine whether the fault is a fault or a thrust fault. The principle of inclusions and components states that, with rocks, if inclusions are found in a formation. For example, in rocks, it is common for gravel from an older formation to be ripped up. A similar situation with igneous rocks occurs when xenoliths are found and these foreign bodies are picked up as magma or lava flows, and are incorporated, later to cool in the matrix. As a result, xenoliths are older than the rock which contains them, the principle of original horizontality states that the deposition of sediments occurs as essentially horizontal beds
5.
Recorded history
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Recorded history or written history is a historical narrative based on a written record or other documented communication. Recorded history can be contrasted with other narratives of the past, for broader world history, recorded history begins with the accounts of the ancient world around the 4th millennium BC, and coincides with the invention of writing. Examples of written texts, however, can be found dating as far back as 1750 BCE in Ancient Mesopotamia, for some geographic regions or cultures, written history is limited to a relatively recent period in human history because of the limited use of written records. Because of these limits, recorded history in different contexts may refer to different periods of time depending on the historical topic. The question of the nature, and even the possibility, of a method for interpreting recorded history is raised in the philosophy of history as a question of epistemology. Prehistory traditionally refers to the span of time before recorded history, prehistory refers to the past in an area where no written records exist, or where the writing of a culture is not understood. Protohistory refers to the period between prehistory and history, after the advent of literacy in a society but before the writings of the first historians. Protohistory may also refer to the period during which a culture or civilization has not yet developed writing, more complete writing systems were preceded by proto-writing. Early examples are the Jiahu symbols, Vinča signs, early Indus script, earliest recorded history, which varies greatly in quality and reliability, deals with Pharaohs and their reigns, made by ancient Egyptians. Much of the earliest recorded history was re-discovered relatively recently due to archaeological dig sites findings, since these initial accounts, a number of different traditions have developed in different parts of the world in how to handle the writing and production of historical accounts. In China, the earliest history was recorded in oracle bone script which was deciphered, the Zuo Zhuan, attributed to Zuo Qiuming in the 5th century BCE, is the earliest written of narrative history in the world and covers the period from 722 to 468 BCE. The Classic of History is one of the Five Classics of Chinese classic texts and it is traditionally attributed to Confucius. Zhan Guo Ce was a renowned ancient Chinese historical compilation of materials on the Warring States period compiled between the 3rd and 1st centuries BCE. Sima Qian was the first in China to lay the groundwork for professional historical writing and his written work was the Shiji, a monumental lifelong achievement in literature. His work influenced every subsequent author of history in China, including the prestigious Ban family of the Eastern Han Dynasty era, Herodotus of Halicarnassus has generally been acclaimed as the father of history composing his The Histories written from 450s to the 420s BCE. However, his contemporary Thucydides is credited with having first approached history with a historical method in his work the History of the Peloponnesian War. Thucydides, unlike Herodotus, regarded history as being the product of the choices and actions of human beings, saint Augustine was influential in Christian and Western thought at the beginning of the medieval period. Through the Medieval and Renaissance periods, history was studied through a sacred or religious perspective
6.
Dendrochronology
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Dendrochronology is the scientific method of dating tree rings to the exact year they were formed in order to analyze atmospheric conditions during different periods in history. Dendrochronology is useful for determining the timing of events and rates of change in the environment and also in works of art and architecture, such as old panel paintings on wood, buildings and it is also used in radiocarbon dating to calibrate radiocarbon ages. New growth in trees occurs in a layer of cells near the bark, a trees growth rate changes in a predictable pattern throughout the year in response to seasonal climate changes, resulting in visible growth rings. Each ring marks a complete cycle of seasons, or one year, as of 2013, the oldest tree-ring measurements in the Northern Hemisphere extend back 13,900 years. Dendrochronology derives from Ancient Greek, δένδρον, meaning tree limb, χρόνος, meaning time, and -λογία, the Greek botanist Theophrastus first mentioned that the wood of trees has rings. In his Trattato della Pittura, Leonardo da Vinci was the first person to mention that trees form rings annually, in 1737, French investigators Henri-Louis Duhamel du Monceau and Georges-Louis Leclerc de Buffon examined the effect of growing conditions on the shape of tree rings. They found that in 1709, a severe winter produced a distinctly dark tree ring, the English polymath Charles Babbage proposed using dendrochronology to date the remains of trees in peat bogs or even in geological strata. During the latter half of the century, the scientific study of tree rings. In 1859, the German-American Jacob Kuechler used crossdating to examine oaks in order to study the record of climate in western Texas, in 1866, the German botanist, entomologist, and forester Julius Ratzeburg observed the effects on tree rings of defoliation caused by insect infestations. By 1882, this observation was already appearing in forestry textbooks, in the 1870s, the Dutch astronomer Jacobus C. Kapteyn was using crossdating to reconstruct the climates of the Netherlands, in 1881, the Swiss-Austrian forester Arthur von Seckendorff-Gudent was using crossdating. From 1869 to 1901, Robert Hartig, a German professor of forest pathology, wrote a series of papers on the anatomy, in 1892, the Russian physicist Fedor Nikiforovich Shvedov wrote that he had used patterns found in tree rings to predict droughts in 1882 and 1891. During the first half of the 20th century, the astronomer A. E. Douglass founded the Laboratory of Tree-Ring Research at the University of Arizona. Growth rings, also referred to as tree rings or annual rings, growth rings are the result of new growth in the vascular cambium, a layer of cells near the bark that is classified as a lateral meristem, this growth in diameter is known as secondary growth. Visible rings result from the change in speed through the seasons of the year, thus, critical for the title method. If the bark of the tree has been removed in a particular area, the rings are more visible in temperate zones, where the seasons differ more markedly. The inner portion of a ring is formed early in the growing season, when growth is comparatively rapid and is known as early wood. Many trees in temperate zones make one growth ring each year, hence, for the entire period of a trees life, a year-by-year record or ring pattern is formed that reflects the age of the tree and the climatic conditions in which the tree grew
7.
Radiocarbon dating
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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. The method was developed by Willard Libby in the late 1940s, Libby received the Nobel Prize for his work in 1960. The radiocarbon dating method is based on the fact that radiocarbon is constantly being created in the atmosphere by the interaction of cosmic rays with atmospheric nitrogen. The resulting radiocarbon combines with oxygen to form radioactive carbon dioxide. When the animal or plant dies, it stops exchanging carbon with its environment, and from that point onwards the amount of 14C it contains begins to decrease as the 14C undergoes radioactive decay. Measuring the amount of 14C in a sample from a plant or animal such as a piece of wood or a fragment of bone provides information that can be used to calculate when the animal or plant died. The idea behind radiocarbon dating is straightforward, but years of work were required to develop the technique to the point where accurate dates could be obtained. Research has been ongoing since the 1960s to determine what the proportion of 14C in the atmosphere has been over the past fifty thousand years. The resulting data, in the form of a curve, is now used to convert a given measurement of radiocarbon in a sample into an estimate of the samples calendar age. Other corrections must be made to account for the proportion of 14C in different types of organisms, additional complications come from the burning of fossil fuels such as coal and oil, and from the above-ground nuclear tests done in the 1950s and 1960s. Conversely, nuclear testing increased the amount of 14C in the atmosphere, measurement of radiocarbon was originally done by beta-counting devices, which counted the amount of beta radiation emitted by decaying 14C atoms in a sample. The development of dating has had a profound impact on archaeology. In addition to permitting more accurate dating within archaeological sites than previous methods, histories of archaeology often refer to its impact as the radiocarbon revolution. Radiocarbon dating has allowed key transitions in prehistory to be dated, such as the end of the last ice age, and they synthesized 14C using the laboratorys cyclotron accelerator and soon discovered that the atoms half-life was far longer than had been previously thought. This was followed by a prediction by Serge A. Korff, then employed at the Franklin Institute in Philadelphia and it had previously been thought that 14C would be more likely to be created by deuterons interacting with 13C. At some time during World War II, Willard Libby, who was then at Berkeley, learned of Korffs research, in 1945, Libby moved to the University of Chicago where he began his work on radiocarbon dating. He published a paper in 1946 in which he proposed that the carbon in living matter might include 14C as well as non-radioactive carbon, by contrast, methane created from petroleum showed no radiocarbon activity because of its age. The results were summarized in a paper in Science in 1947, Libby and James Arnold proceeded to test the radiocarbon dating theory by analyzing samples with known ages
8.
Thermoluminescence dating
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As a crystalline material is heated during measurements the process of thermoluminescence starts. Thermoluminescence emits a light signal that is proportional to the radiation dose absorbed by the material. It is a type of luminescence dating, the technique has wide application, and is relatively cheap at some US$300–700 per object, ideally a number of samples are tested. Sediments are more expensive to date, the destruction of a relatively significant amount of sample material is necessary, which can be a limitation in the case of artworks. The heating must have taken the object above 500° C, which covers most ceramics and it will often work well with stones that have been heated by fire. The clay core of bronze sculptures made by lost wax casting can also be tested, different materials vary considerably in their suitability for the technique, depending on several factors. Subsequent irradiation, for if an x-ray is taken, can affect accuracy. Ideally this is assessed by measurements made at the precise findspot over a long period, for artworks, it may be sufficient to confirm whether a piece is broadly ancient or modern, and this may be possible even if a precise date cannot be estimated. These imperfections lead to local humps and dips in the crystalline materials electric potential, where there is a dip, a free electron may be attracted and trapped. The flux of ionizing radiation—both from cosmic radiation and from natural radioactivity—excites electrons from atoms in the lattice into the conduction band where they can move freely. Most excited electrons will recombine with lattice ions, but some will be trapped. Depending on the depth of the traps the storage time of trapped electrons will vary as some traps are sufficiently deep to store charge for hundreds of thousands of years. In the process of recombining with an ion, they lose energy and emit photons. The amount of light produced is proportional to the number of trapped electrons that have been freed which is in turn proportional to the dose accumulated. In order to relate the signal to the dose that caused it, it is necessary to calibrate the material with known doses of radiation since the density of traps is highly variable. Thermoluminescence dating presupposes a zeroing event in the history of the material, either heating or exposure to sunlight, therefore, at that point the thermoluminescence signal is zero. As time goes on, the radiation field around the material causes the trapped electrons to accumulate. In the laboratory, the radiation dose can be measured
