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72-605: The Northern Dvina forms a delta entering the Dvina Bay, with many islands separating different streams. There are many small islands in the Dvina Bay as well, the biggest being Mudyug Island . A national park, Onezhskoye Pomorye National Park , was open on the Onega Peninsula on 26 February 2013. The Dvina Bay is limited by the Onega Peninsula from the west. At the eastern side, the shore steeply rises to

144-432: A density current that deposits its sediments as turbidites . When the river water is less dense than the basin water, as is typical of river deltas on an ocean coastline, the delta is characterized by hypopycnal flow in which the river water is slow to mix with the denser basin water and spreads out as a surface fan. This allows fine sediments to be carried a considerable distance before settling out of suspension. Beds in

216-473: A boy living on the island of Samos, to which he had fled with his family from the oppressions of Lygdamis, tyrant of Halicarnassus and grandson of Artemisia. Panyassis , the epic poet related to Herodotus, is reported to have taken part in a failed uprising. The Suda also states that Herodotus later returned home to lead the revolt that eventually overthrew the tyrant. Due to recent discoveries of inscriptions at Halicarnassus dated to about Herodotus's time, it

288-493: A common location for civilizations to flourish due to access to flat land for farming, freshwater for sanitation and irrigation , and sea access for trade. Deltas often host extensive industrial and commercial activities, and agricultural land is frequently in conflict. Some of the world's largest regional economies are located on deltas such as the Pearl River Delta , Yangtze River Delta , European Low Countries and

360-545: A delta but enter into the sea in the form of an estuary . Notable examples include the Gulf of Saint Lawrence and the Tagus estuary. In rare cases, the river delta is located inside a large valley and is called an inverted river delta . Sometimes a river divides into multiple branches in an inland area, only to rejoin and continue to the sea. Such an area is called an inland delta , and often occurs on former lake beds. The term

432-533: A fan. The more often the flow changes course, the shape develops closer to an ideal fan because more rapid changes in channel position result in a more uniform deposition of sediment on the delta front. The Mississippi and Ural River deltas, with their bird's feet, are examples of rivers that do not avulse often enough to form a symmetrical fan shape. Alluvial fan deltas, as seen by their name, avulse frequently and more closely approximate an ideal fan shape. Most large river deltas discharge to intra-cratonic basins on

504-399: A few main distributaries. Once a wave-dominated or river-dominated distributary silts up, it is abandoned, and a new channel forms elsewhere. In a tidal delta, new distributaries are formed during times when there is a lot of water around – such as floods or storm surges . These distributaries slowly silt up at a more or less constant rate until they fizzle out. A tidal freshwater delta is

576-545: A flat arid area splits into channels that evaporate as it progresses into the desert. The Okavango Delta in Botswana is one example. See endorheic basin . The generic term mega delta can be used to describe very large Asian river deltas, such as the Yangtze , Pearl , Red , Mekong , Irrawaddy , Ganges-Brahmaputra , and Indus . The formation of a delta is complicated, multiple, and cross-cutting over time, but in

648-664: A historical topic more in keeping with the Greek world-view: focused on the context of the polis or city-state. The interplay of civilizations was more relevant to Greeks living in Anatolia, such as Herodotus himself, for whom life within a foreign civilization was a recent memory. Before the Persian crisis, history had been represented among the Greeks only by local or family traditions. The "Wars of Liberation" had given to Herodotus

720-573: A hypocynal delta dip at a very shallow angle, around 1 degree. Fluvial-dominated deltas are further distinguished by the relative importance of the inertia of rapidly flowing water, the importance of turbulent bed friction beyond the river mouth, and buoyancy . Outflow dominated by inertia tends to form Gilbert-type deltas. Outflow dominated by turbulent friction is prone to channel bifurcation, while buoyancy-dominated outflow produces long distributaries with narrow subaqueous natural levees and few channel bifurcations. The modern Mississippi River delta

792-524: A later citizen of Thurii in modern Calabria , Italy. He wrote the Histories , a detailed account of the Greco-Persian Wars , and was the first writer to apply a scientific method to historical events. He has been described as " The Father of History ", a title conferred on him by the ancient Roman orator Cicero , and the " Father of Lies " by others. The Histories primarily cover

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864-404: A literary critic of Augustan Rome , listed seven predecessors of Herodotus, describing their works as simple unadorned accounts of their own and other cities and people, Greek or foreign, including popular legends, sometimes melodramatic and naïve, often charming – all traits that can be found in the work of Herodotus himself. Modern historians regard the chronology as uncertain, but according to

936-439: A mature delta with a distributary network. Another way these distributary networks form is from the deposition of mouth bars (mid-channel sand and/or gravel bars at the mouth of a river). When this mid-channel bar is deposited at the mouth of a river, the flow is routed around it. This results in additional deposition on the upstream end of the mouth bar, which splits the river into two distributary channels. A good example of

1008-534: A native of Halicarnassus in Anatolia , and it is generally accepted that he was born there around 485 BC. The Suda says his family was influential, that he was the son of Lyxes and Dryo and the brother of Theodorus, and that he was also related to Panyassis – an epic poet of the time. Halicarnassus was then within the Persian Empire , making Herodotus a Persian subject, and it may be that

1080-592: A plateau ( White Sea - Kuloy Plateau ) which drains east into the Soyana , a major tributary of the Kuloy . The Onega Peninsula shore is often referred to as Letny Bereg ( Summer Coast ), and the eastern shore of the bay is Zimny Bereg ( Winter Coast ). The names reflect the fact that the Pomors of the Dvina Bay were fishing at Summer Coast and Winter Coast in the summer and in the winter, respectively. The Dvina Bay coast

1152-423: A sedimentary deposit formed at the boundary between an upland stream and an estuary, in the region known as the "subestuary". Drowned coastal river valleys that were inundated by rising sea levels during the late Pleistocene and subsequent Holocene tend to have dendritic estuaries with many feeder tributaries. Each tributary mimics this salinity gradient from its brackish junction with the mainstem estuary up to

1224-447: A simple delta three main types of bedding may be distinguished: the bottomset beds, foreset/frontset beds, and topset beds. This three-part structure may be seen on small scale by crossbedding . Human activities in both deltas and the river basins upstream of deltas can radically alter delta environments. Upstream land use change such as anti-erosion agricultural practices and hydrological engineering such as dam construction in

1296-696: A version of the Histories written by "Herodotus of Thurium", and some passages in the Histories have been interpreted as proof that he wrote about Magna Graecia from personal experience there (IV, 15,99; VI, 127). According to Ptolemaeus Chennus , a late source summarized in the Library of Photius , Plesirrhous the Thessalian, the hymnographer, was the eromenos of Herodotus and his heir. This account has also led some historians to assume Herodotus died childless. Intimate knowledge of some events in

1368-520: A young Thucydides happened to be in the assembly with his father, and burst into tears during the recital. Herodotus observed prophetically to the boy's father: "Your son's soul yearns for knowledge." Eventually, Thucydides and Herodotus became close enough for both to be interred in Thucydides's tomb in Athens. Such at least was the opinion of Marcellinus in his Life of Thucydides . According to

1440-551: Is a good example of a fluvial-dominated delta whose outflow is buoyancy-dominated. Channel abandonment has been frequent, with seven distinct channels active over the last 5000 years. Other fluvial-dominated deltas include the Mackenzie delta and the Alta delta. A Gilbert delta (named after Grove Karl Gilbert ) is a type of fluvial-dominated delta formed from coarse sediments, as opposed to gently sloping muddy deltas such as that of

1512-491: Is a major sign that Mars once had large amounts of water. Deltas have been found over a wide geographical range. Below are pictures of a few. Herodotus Herodotus ( Ancient Greek : Ἡρόδοτος , romanized :  Hēródotos ; c.  484  – c.  425 BC) was a Greek historian and geographer from the Greek city of Halicarnassus , part of the Persian Empire (now Bodrum , Turkey) and

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1584-591: Is called by the Ionians ", including describing the outflow of silt into the sea and the convexly curved seaward side of the triangle. Despite making comparisons to other river systems deltas, Herodotus did not describe them as "deltas". The Greek historian Polybius likened the land between the Rhône and Isère rivers to the Nile Delta, referring to both as islands, but did not apply the word delta. According to

1656-640: Is consistent with a tyrant under pressure. His name is not mentioned later in the tribute list of the Athenian Delian League , indicating that there might well have been a successful uprising against him some time before 454 BC. Herodotus wrote his Histories in the Ionian dialect , in spite of being born in a Dorian settlement. According to the Suda , Herodotus learned the Ionian dialect as

1728-491: Is generally assumed that he died not long afterwards, possibly before his sixtieth year. Herodotus would have made his researches known to the larger world through oral recitations to a public crowd. John Marincola writes in his introduction to the Penguin edition of the Histories that there are certain identifiable pieces in the early books of Herodotus's work which could be labeled as "performance pieces". These portions of

1800-809: Is now known that the Ionic dialect was used in Halicarnassus in some official documents, so there is no need to assume (like the Suda ) that he must have learned the dialect elsewhere. The Suda is the only source placing Herodotus as the heroic liberator of his birthplace, casting doubt upon the veracity of that romantic account. As Herodotus himself reveals, Halicarnassus, though a Dorian city, had ended its close relations with its Dorian neighbours after an unseemly quarrel (I, 144), and it had helped pioneer Greek trade with Egypt (II, 178). It was, therefore, an outward-looking, international-minded port within

1872-609: Is on account of the many strange stories and the folk-tales he reported that his critics have branded him "The Father of Lies". Even his own contemporaries found reason to scoff at his achievement. In fact, one modern scholar has wondered whether Herodotus left his home in Greek Anatolia , migrating westwards to Athens and beyond, because his own countrymen had ridiculed his work, a circumstance possibly hinted at in an epitaph said to have been dedicated to Herodotus at one of his three supposed resting places, Thuria : Herodotus

1944-548: Is so named because the shape of the Nile Delta approximates the triangular uppercase Greek letter delta . The triangular shape of the Nile Delta was known to audiences of classical Athenian drama ; the tragedy Prometheus Bound by Aeschylus refers to it as the "triangular Nilotic land", though not as a "delta". Herodotus 's description of Egypt in his Histories mentions the Delta fourteen times, as "the Delta, as it

2016-535: The Alcmaeonids , a clan whose history is featured frequently in his writing. According to Plutarch , Herodotus was granted a financial reward by the Athenian assembly in recognition of his work. Plutarch, using Diyllus as a source, says this was 10 talents . In 443 BC or shortly afterwards, he migrated to Thurii , in modern Calabria , as part of an Athenian-sponsored colony . Aristotle refers to

2088-491: The Euphrates to Babylon . For some reason, possibly associated with local politics, he subsequently found himself unpopular in Halicarnassus, and sometime around 447 BC, migrated to Periclean Athens  – a city whose people and democratic institutions he openly admired (V, 78). Athens was also the place where he came to know the local topography (VI, 137; VIII, 52–55), as well as leading citizens such as

2160-662: The Greater Tokyo Area . The Ganges–Brahmaputra Delta , which spans most of Bangladesh and West Bengal and empties into the Bay of Bengal , is the world's largest delta. The Selenga River delta in the Russian republic of Buryatia is the largest delta emptying into a body of fresh water, in its case Lake Baikal . Researchers have found a number of examples of deltas that formed in Martian lakes . Finding deltas

2232-532: The Nile Delta and Colorado River Delta are some of the most extreme examples of the devastation caused to deltas by damming and diversion of water. Historical data documents show that during the Roman Empire and Little Ice Age (times when there was considerable anthropogenic pressure), there was significant sediment accumulation in deltas. The industrial revolution has only amplified the impact of humans on delta growth and retreat. Ancient deltas benefit

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2304-772: The Peloponnesian War on the abduction of some prostitutes – a mocking reference to Herodotus, who reported the Persians' account of their wars with Greece , beginning with the rapes of the mythical heroines Io , Europa , Medea , and Helen . Similarly, the Athenian historian Thucydides dismissed Herodotus as a story-teller. Thucydides, who had been trained in rhetoric , became the model for subsequent prose-writers as an author who seeks to appear firmly in control of his material, whereas with his frequent digressions Herodotus appeared to minimize (or possibly disguise) his authorial control. Moreover, Thucydides developed

2376-513: The Persian Empire , and the historian's family could well have had contacts in other countries under Persian rule, facilitating his travels and his researches. Herodotus's eyewitness accounts indicate that he traveled in Egypt in association with Athenians, probably sometime after 454 BC or possibly earlier, after an Athenian fleet had assisted the uprising against Persian rule in 460–454 BC. He probably traveled to Tyre next and then down

2448-581: The Suda , he was buried in Macedonian Pella and in the agora in Thurii. Herodotus announced the purpose and scope of his work at the beginning of his Histories: Here are presented the results of the inquiry carried out by Herodotus of Halicarnassus. The purpose is to prevent the traces of human events from being erased by time, and to preserve the fame of the important and remarkable achievements produced by both Greeks and non-Greeks; among

2520-426: The sediments that are carried by the waters of a river , where the river merges with a body of slow-moving water or with a body of stagnant water. The creation of a river delta occurs at the river mouth , where the river merges into an ocean , a sea , or an estuary , into a lake , a reservoir , or (more rarely) into another river that cannot carry away the sediment supplied by the feeding river. Etymologically,

2592-648: The Greek geographer Strabo , the Cynic philosopher Onesicritus of Astypalaea , who accompanied Alexander the Great 's conquests in India , reported that Patalene (the delta of the Indus River ) was "a delta" ( Koinē Greek : καλεῖ δὲ τὴν νῆσον δέλτα , romanized:  kalei de tēn nēson délta , lit.   'he calls the island a delta'). The Roman author Arrian 's Indica states that "the delta of

2664-503: The Mississippi. For example, a mountain river depositing sediment into a freshwater lake would form this kind of delta. It is commonly a result of homopycnal flow. Such deltas are characterized by a tripartite structure of topset, foreset, and bottomset beds. River water entering the lake rapidly deposits its coarser sediments on the submerged face of the delta, forming steeping dipping foreset beds. The finer sediments are deposited on

2736-472: The ability to pile up and accumulate due to the sediment traveling into a steep subduction trench rather than a shallow continental shelf . There are many other lesser factors that could explain why the majority of river deltas form along passive margins rather than active margins. Along active margins, orogenic sequences cause tectonic activity to form over-steepened slopes, brecciated rocks, and volcanic activity resulting in delta formation to exist closer to

2808-407: The ancient account, these predecessors included Dionysius of Miletus , Charon of Lampsacus, Hellanicus of Lesbos , Xanthus of Lydia and, the best attested of them all, Hecataeus of Miletus . Of these, only fragments of Hecataeus's works survived, and the authenticity of these is debatable, but they provide a glimpse into the kind of tradition within which Herodotus wrote his own Histories . It

2880-591: The audience. It was conventional in Herodotus's day for authors to "publish" their works by reciting them at popular festivals. According to Lucian , Herodotus took his finished work straight from Anatolia to the Olympic Games and read the entire Histories to the assembled spectators in one sitting, receiving rapturous applause at the end of it. According to a very different account by an ancient grammarian, Herodotus refused to begin reading his work at

2952-1256: The basins feeding deltas have reduced river sediment delivery to many deltas in recent decades. This change means that there is less sediment available to maintain delta landforms, and compensate for erosion and sea level rise , causing some deltas to start losing land. Declines in river sediment delivery are projected to continue in the coming decades. The extensive anthropogenic activities in deltas also interfere with geomorphological and ecological delta processes. People living on deltas often construct flood defences which prevent sedimentation from floods on deltas, and therefore means that sediment deposition can not compensate for subsidence and erosion . In addition to interference with delta aggradation , pumping of groundwater , oil , and gas , and constructing infrastructure all accelerate subsidence , increasing relative sea level rise. Anthropogenic activities can also destabilise river channels through sand mining , and cause saltwater intrusion . There are small-scale efforts to correct these issues, improve delta environments and increase environmental sustainability through sedimentation enhancing strategies . While nearly all deltas have been impacted to some degree by humans,

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3024-422: The bird's-foot of the Mississippi or Ural river deltas), pushing its mouth into the standing water. As the deltaic lobe advances, the gradient of the river channel becomes lower because the river channel is longer but has the same change in elevation (see slope ). As the gradient of the river channel decreases, the amount of shear stress on the bed decreases, which results in the deposition of sediment within

3096-408: The challenge is great: The data are so few – they rest upon such late and slight authority; they are so improbable or so contradictory, that to compile them into a biography is like building a house of cards, which the first breath of criticism will blow to the ground. Still, certain points may be approximately fixed ... Herodotus was, according to his own statement, at the beginning of his work,

3168-450: The channel and a rise in the channel bed relative to the floodplain . This destabilizes the river channel. If the river breaches its natural levees (such as during a flood), it spills out into a new course with a shorter route to the ocean, thereby obtaining a steeper, more stable gradient. Typically, when the river switches channels in this manner, some of its flow remains in the abandoned channel. Repeated channel-switching events build up

3240-619: The economy due to their well-sorted sand and gravel . Sand and gravel are often quarried from these old deltas and used in concrete for highways , buildings, sidewalks, and landscaping. More than 1 billion tons of sand and gravel are produced in the United States alone. Not all sand and gravel quarries are former deltas, but for ones that are, much of the sorting is already done by the power of water. Urban areas and human habitation tend to be located in lowlands near water access for transportation and sanitation . This makes deltas

3312-439: The festival of Olympia until some clouds offered him a bit of shade – by which time the assembly had dispersed. (Hence the proverbial expression "Herodotus and his shade" to describe someone who misses an opportunity through delay.) Herodotus's recitation at Olympia was a favourite theme among ancient writers, and there is another interesting variation on the story to be found in the Suda : that of Photius and Tzetzes , in which

3384-422: The first genuinely historical inspiration felt by a Greek. These wars showed him that there was a corporate life, higher than that of the city, of which the story might be told; and they offered to him as a subject the drama of the collision between East and West. With him, the spirit of history was born into Greece; and his work, called after the nine Muses, was indeed the first utterance of Clio . Though Herodotus

3456-505: The first years of the Peloponnesian War (VI, 91; VII, 133, 233; IX, 73) suggests that he returned to Athens, in which case it is possible that he died there during an outbreak of the plague. It is also possible he died in Macedonia instead, after obtaining the patronage of the court there; or else he died back in Thurii. There is nothing in the Histories that can be dated to later than 430 BC with any certainty, and it

3528-414: The flow enters the standing water, it is no longer confined to its channel and expands in width. This flow expansion results in a decrease in the flow velocity , which diminishes the ability of the flow to transport sediment . As a result, sediment drops out of the flow and is deposited as alluvium , which builds up to form the river delta. Over time, this single channel builds a deltaic lobe (such as

3600-506: The fresh stream feeding the head of tidal propagation. As a result, the tributaries are considered to be "subestuaries". The origin and evolution of a tidal freshwater delta involves processes that are typical of all deltas as well as processes that are unique to the tidal freshwater setting. The combination of processes that create a tidal freshwater delta result in a distinct morphology and unique environmental characteristics. Many tidal freshwater deltas that exist today are directly caused by

3672-466: The geomorphology and ecosystem. Deltas are typically classified according to the main control on deposition, which is a combination of river, wave , and tidal processes, depending on the strength of each. The other two factors that play a major role are landscape position and the grain size distribution of the source sediment entering the delta from the river. Fluvial-dominated deltas are found in areas of low tidal range and low wave energy. Where

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3744-406: The lake bottom beyond this steep slope as more gently dipping bottomset beds. Behind the delta front, braided channels deposit the gently dipping beds of the topset on the delta plain. While some authors describe both lacustrine and marine locations of Gilbert deltas, others note that their formation is more characteristic of the freshwater lakes, where it is easier for the river water to mix with

3816-594: The lakewater faster (as opposed to the case of a river falling into the sea or a salt lake, where less dense fresh water brought by the river stays on top longer). Gilbert himself first described this type of delta on Lake Bonneville in 1885. Elsewhere, similar structures occur, for example, at the mouths of several creeks that flow into Okanagan Lake in British Columbia and form prominent peninsulas at Naramata , Summerland , and Peachland . In wave-dominated deltas, wave-driven sediment transport controls

3888-583: The land of the Indians is made by the Indus river no less than is the case with that of Egypt". As a generic term for the landform at the mouth of the river, the word delta is first attested in the English-speaking world in the late 18th century, in the work of Edward Gibbon . River deltas form when a river carrying sediment reaches a body of water, such as a lake, ocean, or a reservoir . When

3960-629: The lives of prominent kings and famous battles such as Marathon , Thermopylae , Artemisium , Salamis , Plataea , and Mycale . His work deviates from the main topics to provide a cultural, ethnographical , geographical, and historiographical background that forms an essential part of the narrative and provides readers with a wellspring of additional information. Herodotus was criticized in ancient times for his inclusion of "legends and fanciful accounts" in his work. The contemporaneous historian Thucydides accused him of making up stories for entertainment. He retorted that he reported what he could see and

4032-424: The matters covered is, in particular, the cause of the hostilities between Greeks and non-Greeks. His record of the achievements of others was an achievement in itself, though the extent of it has been debated. Herodotus's place in history and his significance may be understood according to the traditions within which he worked. His work is the earliest Greek prose to have survived intact. Dionysius of Halicarnassus ,

4104-524: The onset of or changes in historical land use, especially deforestation , intensive agriculture , and urbanization . These ideas are well illustrated by the many tidal freshwater deltas prograding into Chesapeake Bay along the east coastline of the United States. Research has demonstrated that the accumulating sediments in this estuary derive from post-European settlement deforestation, agriculture, and urban development. Other rivers, particularly those on coasts with significant tidal range , do not form

4176-468: The research seem independent and "almost detachable", so that they might have been set aside by the author for the purposes of an oral performance. The intellectual matrix of the 5th century, Marincola suggests, comprised many oral performances in which philosophers would dramatically recite such detachable pieces of their work. The idea was to criticize previous arguments on a topic and emphatically and enthusiastically insert their own in order to win over

4248-487: The result of this process is the Wax Lake Delta . In both of these cases, depositional processes force redistribution of deposition from areas of high deposition to areas of low deposition. This results in the smoothing of the planform (or map-view) shape of the delta as the channels move across its surface and deposit sediment. Because the sediment is laid down in this fashion, the shape of these deltas approximates

4320-478: The river delta of the Northern Dvina, both Winter and Summer coasts are remote, with sea and air being the only connections to the villages. There is regular sea navigation in the summer, serving all of the villages. 65°00′N 39°13′E  /  65.000°N 39.217°E  / 65.000; 39.217 River delta A river delta is a triangular landform created by the deposition of

4392-579: The river delta, causing the delta to retreat. For deltas that form further upriver in an estuary, there are complex yet quantifiable linkages between winds, tides, river discharge, and delta water levels. Erosion is also an important control in tide-dominated deltas, such as the Ganges Delta , which may be mainly submarine, with prominent sandbars and ridges. This tends to produce a "dendritic" structure. Tidal deltas behave differently from river-dominated and wave-dominated deltas, which tend to have

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4464-414: The river water is nearly equal in density to the basin water, the delta is characterized by homopycnal flow , in which the river water rapidly mixes with basin water and abruptly dumps most of its sediment load. Where the river water has a higher density than basin water, typically from a heavy load of sediment, the delta is characterized by hyperpycnal flow in which the river water hugs the basin bottom as

4536-399: The sediment is never piled up in thick sequences due to the sediment traveling and depositing in deep subduction trenches. At the mouth of a river, the change in flow conditions can cause the river to drop any sediment it is carrying. This sediment deposition can generate a variety of landforms, such as deltas, sand bars, spits, and tie channels. Landforms at the river mouth drastically alter

4608-514: The sediment source. When sediment does not travel far from the source, sediments that build up are coarser grained and more loosely consolidated, therefore making delta formation more difficult. Tectonic activity on active margins causes the formation of river deltas to form closer to the sediment source which may affect channel avulsion , delta lobe switching, and auto cyclicity. Active margin river deltas tend to be much smaller and less abundant but may transport similar amounts of sediment. However,

4680-424: The shape of the delta, and much of the sediment emanating from the river mouth is deflected along the coastline. The relationship between waves and river deltas is quite variable and largely influenced by the deepwater wave regimes of the receiving basin. With a high wave energy near shore and a steeper slope offshore, waves will make river deltas smoother. Waves can also be responsible for carrying sediments away from

4752-474: The son of Sphynx lies; in Ionic history without peer; a Dorian born, who fled from slander's brand and made in Thuria his new native land. Yet it was in Athens where his most formidable contemporary critics could be found. In 425 BC, which is about the time that Herodotus is thought by many scholars to have died, the Athenian comic dramatist Aristophanes created The Acharnians , in which he blames

4824-754: The term river delta derives from the triangular shape (Δ) of the uppercase Greek letter delta . In hydrology , the dimensions of a river delta are determined by the balance between the watershed processes that supply sediment and the watershed processes that redistribute, sequester, and export the supplied sediment into the receiving basin. River deltas are important in human civilization , as they are major agricultural production centers and population centers. They can provide coastline defence and can impact drinking water supply. They are also ecologically important, with different species' assemblages depending on their landscape position. On geologic timescales , they are also important carbon sinks . A river delta

4896-656: The trailing edges of passive margins due to the majority of large rivers such as the Mississippi , Nile , Amazon , Ganges , Indus , Yangtze , and Yellow River discharging along passive continental margins. This phenomenon is due mainly to three factors: topography , basin area, and basin elevation. Topography along passive margins tend to be more gradual and widespread over a greater area enabling sediment to pile up and accumulate over time to form large river deltas. Topography along active margins tends to be steeper and less widespread, which results in sediments not having

4968-404: The young Herodotus heard local eyewitness accounts of events within the empire and of Persian preparations for the invasion of Greece , including the movements of the local fleet under the command of Artemisia I of Caria . Inscriptions recently discovered at Halicarnassus indicate that Artemesia's grandson Lygdamis negotiated with a local assembly to settle disputes over seized property, which

5040-732: Was first coined by Alexander von Humboldt for the middle reaches of the Orinoco River , which he visited in 1800. Other prominent examples include the Inner Niger Delta , Peace–Athabasca Delta , the Sacramento–San Joaquin River Delta , and the Sistan delta of Iran. The Danube has one in the valley on the Slovak–Hungarian border between Bratislava and Iža . In some cases, a river flowing into

5112-565: Was populated by Russians ( Novgorodians , of whom the Pomors are the descendants) and Karelians , both not later than in the 13th century. Until the 18th century, when Saint Petersburg was founded, Arkhangelsk was the only sea harbour of Russia, and the Northern Dvina and the Dvina Bay were main connection of Russia with the outside world. Most of the villages at the Dvina Bay coast such as Pertominsk , Lopshenga , or Yarenga , are old Pomor villages still depending on fishery. Except for vicinity of

5184-464: Was told. A sizable portion of the Histories has since been confirmed by modern historians and archaeologists . Modern scholars generally turn to Herodotus's own writing for reliable information about his life, supplemented with ancient yet much later sources, such as the Byzantine Suda , an 11th-century encyclopedia which possibly took its information from traditional accounts. Still,

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