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33-420: The primary lithology consists of 1 mm thick varve laminations of claystone , with a dark part and a light dolomitic part, which probably correspond to a wet and dry season respectively, alongside rare, several cm thick sandstone interbeds . These were deposited within an ancient freshwater paleolake, that given the number of laminations has been suggested to have existed for over 150,000 years. The top of

66-553: A North American varve chronology. Carl Caldenius visited Patagonia and Tierra del Fuego , and Erik Norin visited central Asia . By this stage, other geologists were investigating varve sequences, including Matti Sauramo who constructed a varve chronology of the last deglaciation in Finland . 1940 saw the publication of a now classic scientific paper by De Geer, the Geochronologia Suecica , in which he presented

99-581: A long-term timescale. However, by 2012, “missing” varves in the Lake Suigetsu sequence were identified in the Lake Suigetsu 2006 Project by overlapping multiple cores and improved varve counting techniques, extending the timescale to 52,800 years. Varves form in a variety of marine and lacustrine depositional environments from seasonal variation in clastic , biological, and chemical sedimentary processes. The classic varve archetype

132-615: A network of sites along the east coast of Sweden was established. The varved sediments exposed in these sites had formed in glaciolacustrine and glacimarine conditions in the Baltic basin as the last ice sheet retreated northwards. By 1914, De Geer had discovered that it was possible to compare varve sequences across long distances by matching variations in varve thickness, and distinct marker laminae. However, this discovery led De Geer and many of his co-workers into making incorrect correlations, which they called 'teleconnections', between continents,

165-481: A period of 9.3 thousand years during an interglacial period in the Pleistocene. Chronology Chronology (from Latin chronologia , from Ancient Greek χρόνος , chrónos , ' time ' ; and -λογία , -logia ) 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 . It is also "the determination of

198-486: A process criticised by other varve pioneers like Ernst Antevs . In 1924, the Geochronological Institute, a special laboratory dedicated to varve research was established. De Geer and his co-workers and students made trips to other countries and continents to investigate varved sediments. Ernst Antevs studied sites from Long Island , U.S.A. to Lake Timiskaming and Hudson Bay , Canada, and created

231-409: Is a light / dark coloured couplet deposited in a lake basin. During summer months, light lamine composed of silica and calcium carbonate are deposited. This is the consequence of dead phytoplankton , and other micro-organisms that create their skeletons or shells out of silica or calcium carbonate, falling to the lake bottom. This process of the precipatation and deposition of dead micro-organisms out of

264-418: Is a long table synchronizing the events from each of the nine kingdoms in parallel columns. By comparing the parallel columns, the reader can determine which events were contemporaneous, or how many years separated two different events. To place all the events on the same time scale, Eusebius used an Anno Mundi (A.M.) era, meaning that events were dated from the supposed beginning of the world as computed from

297-671: Is to synchronize events. By synchronizing an event it becomes possible to relate it to the current time and to compare the event to other events. Among historians, a typical need is to synchronize the reigns of kings and leaders in order to relate the history of one country or region to that of another. For example, the Chronicon of Eusebius (325 A.D.) is one of the major works of historical synchronism. This work has two sections. The first contains narrative chronicles of nine different kingdoms: Chaldean, Assyrian, Median, Lydian, Persian, Hebrew, Greek, Peloponnesian, Asian, and Roman. The second part

330-538: Is used in turn as a calibration reference for radiocarbon dating curves. The familiar terms calendar and era (within the meaning of a coherent system of numbered calendar years) concern two complementary fundamental concepts of chronology. For example, during eight centuries the calendar belonging to the Christian era , which era was taken in use in the 8th century by Bede , was the Julian calendar, but after

363-594: The Book of Genesis in the Hebrew Pentateuch . According to the computation Eusebius used, this occurred in 5199 B.C. The Chronicon of Eusebius was widely used in the medieval world to establish the dates and times of historical events. Subsequent chronographers, such as George Syncellus (died circa 811), analyzed and elaborated on the Chronicon by comparing with other chronologies. The last great chronographer

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396-459: The 3rd millennium BCE, for example. The study of the means of placing pottery and other cultural artifacts into some kind of order proceeds in two phases, classification and typology: Classification creates categories for the purposes of description, and typology seeks to identify and analyse changes that allow artifacts to be placed into sequences. Laboratory techniques developed particularly after mid-20th century helped constantly revise and refine

429-567: The Romans themselves did; the dominant method of identifying Roman years was to name the two consuls who held office that year. Before the advent of the modern critical edition of historical Roman works, AUC was indiscriminately added to them by earlier editors, making it appear more widely used than it actually was. It was used systematically for the first time only about the year 400, by the Iberian historian Orosius . Pope Boniface IV , in about

462-652: The Swedish Time Scale, a floating varve chronology for ice recession from Skåne to Indalsälven . Ragnar Lidén made the first attempts to link this time scale with the present day. Since then, there have been revisions as new sites are discovered, and old ones reassessed. At present, the Swedish varve chronology is based on thousands of sites, and covers 13,200 varve years. In 2008, although varves were considered likely to give similar information to dendrochronology , they were considered "too uncertain" for use on

495-556: The absence of bioturbation . Consequently, varves commonly form under anoxic conditions. A well-known marine example of varved sediments are those found in the Santa Barbara basin, off California . Another long record of varved sediments is the palaeo-lacustrine record of the Piànico–Sèllere Basin (southern Alps). Here, the detrital layer part of each varve was used as a proxy for 771 palaeofloods which occurred over

528-450: The absence of written history , with its chronicles and king lists , late 19th century archaeologists found that they could develop relative chronologies based on pottery techniques and styles. In the field of Egyptology , William Flinders Petrie pioneered sequence dating to penetrate pre-dynastic Neolithic times, using groups of contemporary artefacts deposited together at a single time in graves and working backwards methodically from

561-404: The actual temporal sequence of past events". Chronology is a part of periodization . It is also a part of the discipline of history including earth history , the earth sciences , and study of the geologic time scale . Chronology is the science of locating historical events in time. It relies mostly upon chronometry , which is also known as timekeeping, and historiography , which examines

594-402: 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

627-412: The earliest historical phases of Egypt. This method of dating is known as seriation . Known wares discovered at strata in sometimes quite distant sites, the product of trade, helped extend the network of chronologies. Some cultures have retained the name applied to them in reference to characteristic forms, for lack of an idea of what they called themselves: "The Beaker People " in northern Europe during

660-682: The formation shows the laminations becoming wavy, likely as a result of microbial interactions, and the top of the formation is capped by a conglomerate predominantly composed of black Carboniferous limestone pebbles. The Karabastau Formation was first discovered in 1921 by Soviet geologists, and was declared a protected paleontological reserve in 1924. Batrachognathus B. volans An Anurognathid Pterosaur. Karatausuchus K. sharovi An Atoposaurid Crocodylomorph . Karaurus K. sharovi stem-group salamander . Sordes A Pterodactylomorph Pterosaur. Hundreds of species of insects are known from several localities within

693-559: The formation, primarily Karatau-Mikhailovka Varve A varve is an annual layer of sediment or sedimentary rock . The word 'varve' derives from the Swedish word varv whose meanings and connotations include 'revolution', 'in layers', and 'circle'. The term first appeared as Hvarfig lera (varved clay) on the first map produced by the Geological Survey of Sweden in 1862. Initially, "varve" referred to each of

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726-444: The high levels of salt in normal sea water coagulate the clay into coarse grains. Since the saline waters leave coarse particles all year, it is nearly impossible to distinguish the individual layers in salt waters. Indeed, clay flocculation occurs at high ionic strength due to the collapse of the clay electrical double layer (EDL), which decreases the electrostatic repulsion between negatively charged clay particles. Although

759-701: The literary methods of synchronism used by traditional chronographers such as Eusebius, Syncellus and Scaliger, it is possible to synchronize events by archaeological or astronomical means. For example, the Eclipse of Thales , described in the first book of Herodotus can potentially be used to date the Lydian War because the eclipse took place during the middle of an important battle in that war. Likewise, various eclipses and other astronomical events described in ancient records can be used to astronomically synchronize historical events. Another method to synchronize events

792-470: The most important and illuminating in studies of past climate change . Varves are amongst the smallest-scale events recognised in stratigraphy . An annual layer can be highly visible because the particles washed into the layer in the spring when there is greater flow strength are much coarser than those deposited later in the year. This forms a pair of layers—one coarse and one fine—for each annual cycle. Varves form only in fresh or brackish water, because

825-429: The separate components comprising a single annual layer in glacial lake sediments , but at the 1910 Geological Congress, the Swedish geologist Gerard De Geer (1858–1943) proposed a new formal definition, where varve means the whole of any annual sedimentary layer. More recently introduced terms such as 'annually laminated' are synonymous with varve. Of the many rhythmites in the geological record, varves are one of

858-501: The term varve was not introduced until the late nineteenth century, the concept of an annual rhythm of deposition is at least two centuries old. In the 1840s, Edward Hitchcock suspected laminated sediment in North America could be seasonal, and in 1884 Warren Upham postulated that light-dark laminated couplets represented a single year's deposition. Despite these earlier forays, the chief pioneer and populariser of varve research

891-509: The water column is resticted to warm months when productivity (ecology) is high. The corresponding dark colored layers are composed of organic matter and fine sediment particles transported and deposited during spring freshets as a result of winter snowmelt. The alternation of these two distinct layers allows for high-precision dating of sediment profiles, for each couplet is equivalent to one year. In addition to seasonal variation of sedimentary processes and deposition, varve formation requires

924-426: The writing of history and the use of historical methods. Radiocarbon dating estimates the age of formerly living things by measuring the proportion of carbon-14 isotope in their carbon content. Dendrochronology estimates the age of trees by correlation of the various growth rings in their wood to known year-by-year reference sequences in the region to reflect year-to-year climatic variation. Dendrochronology

957-620: The year 1582 it was the Gregorian calendar. Dionysius Exiguus (about the year 500) was the founder of that era, which is nowadays the most widespread dating system on earth. An epoch is the date (year usually) when an era begins. Ab Urbe condita is Latin for "from the founding of the City ( Rome )", traditionally set in 753 BC. It was used to identify the Roman year by a few Roman historians. Modern historians use it much more frequently than

990-556: The year 1702) and Jacques Cassini (in the year 1740), purely to simplify certain calculations, put the Julian Dating System (proposed in the year 1583 by Joseph Scaliger ) and with it an astronomical era into use, which contains a leap year zero, which precedes the year 1 (AD). 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

1023-461: The year 600, seems to have been the first who made a connection between these this era and Anno Domini . (AD 1 = AUC 754.) Dionysius Exiguus' Anno Domini era (which contains only calendar years AD ) was extended by Bede to the complete Christian era (which contains, in addition all calendar years BC , but no year zero ). Ten centuries after Bede, the French astronomers Philippe de la Hire (in

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1056-540: Was Joseph Justus Scaliger (1540-1609) who reconstructed the lost Chronicon and synchronized all of ancient history in his two major works, De emendatione temporum (1583) and Thesaurus temporum (1606). Much of modern historical datings and chronology of the ancient world ultimately derives from these two works. Scaliger invented the concept of the Julian Day which is still used as the standard unified scale of time for both historians and astronomers. In addition to

1089-558: Was Gerard De Geer. While working for the Geological Survey of Sweden, De Geer noticed a close visual similarity between the laminated sediments he was mapping, and tree-rings . This prompted him to suggest the coarse-fine couplets frequently found in the sediments of glacial lakes were annual layers. The first varve chronology was constructed by De Geer in Stockholm in the late 19th century. Further work soon followed, and

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