96-630: Blue Mud Bay is a large, shallow, partly enclosed bay on the eastern coast of Arnhem Land , in the Northern Territory of Australia, facing Groote Eylandt on the western side of the Gulf of Carpentaria . It lies 580 km (360 mi) east-south-east of Darwin in the Arnhem Coast bioregion . Its name was given to a landmark court ruling affirming that the Aboriginal traditional owners of much of
192-578: A "die on the vine" plan that will "slowly but surely" kill indigenous culture. Born in the 1930s, Dr. Gawirrin Gumana AO was a leader of the Dhalwangu clan , renowned for his artwork and knowledge of traditional culture and law. In May 2009, he had the following to say about the significance of the homelands to his people: Despite facing government concerns and policy confusion, a number of people have developed commercial enterprises that have centred on using
288-677: A day were similar, but at springs the tides rose 7 feet (2.1 m) in the morning but 9 feet (2.7 m) in the evening. Pierre-Simon Laplace formulated a system of partial differential equations relating the ocean's horizontal flow to its surface height, the first major dynamic theory for water tides. The Laplace tidal equations are still in use today. William Thomson, 1st Baron Kelvin , rewrote Laplace's equations in terms of vorticity which allowed for solutions describing tidally driven coastally trapped waves, known as Kelvin waves . Others including Kelvin and Henri Poincaré further developed Laplace's theory. Based on these developments and
384-445: A day—is a third regular category. Tides vary on timescales ranging from hours to years due to a number of factors, which determine the lunitidal interval . To make accurate records, tide gauges at fixed stations measure water level over time. Gauges ignore variations caused by waves with periods shorter than minutes. These data are compared to the reference (or datum) level usually called mean sea level . While tides are usually
480-512: A few days after (or before) new and full moon and are highest around the equinoxes, though Pliny noted many relationships now regarded as fanciful. In his Geography , Strabo described tides in the Persian Gulf having their greatest range when the moon was furthest from the plane of the Equator. All this despite the relatively small amplitude of Mediterranean basin tides. (The strong currents through
576-525: A lower court in March 2007. The High Court ruled that the water lying over Aboriginal land should not be treated differently from the land itself. Ownership of Aboriginal land adjoining marine waters in the Northern Territory generally extends to the low tide level. Since people have always had to obtain permission from the traditional owners or the appropriate land council to go on to Aboriginal land,
672-594: A painting of the wharf at Darwin, including building and boats, and Europeans with hats and pipes, some apparently without hands (which they have in their trouser pockets). Near the East Alligator River crossing, a figure was painted of a man carrying a gun and wearing his hair in long pigtails down his back, characteristic of the Chinese labourers brought to Darwin in the late 19th century. One Yolngu prehistoric stone arrangement at Maccasans Beach near Yirrkala shows
768-512: A smooth sphere covered by a sufficiently deep ocean under the tidal force of a single deforming body is a prolate spheroid (essentially a three-dimensional oval) with major axis directed toward the deforming body. Maclaurin was the first to write about the Earth's rotational effects on motion. Euler realized that the tidal force's horizontal component (more than the vertical) drives the tide. In 1744 Jean le Rond d'Alembert studied tidal equations for
864-514: A system of pulleys to add together six harmonic time functions. It was "programmed" by resetting gears and chains to adjust phasing and amplitudes. Similar machines were used until the 1960s. The first known sea-level record of an entire spring–neap cycle was made in 1831 on the Navy Dock in the Thames Estuary . Many large ports had automatic tide gauge stations by 1850. John Lubbock was one of
960-658: A vigorous traditional culture, and whose name for this area is Miwatj. In West Arnhem Land, large groups include the Bininj people and the Maung people of the Goulburn Islands . In 2018, Kathy Guthadjaka AM (also known as Gotha) was awarded 'NT Senior Australian of the Year.' Guthadjaka has conducted academic research into Aboriginal languages, knowledge, and culture. In 2013–14, the entire region contributed around A$ 1.3 billion or 7% to
1056-505: Is a historical region of the Northern Territory of Australia. It is located in the north-eastern corner of the territory and is around 500 km (310 mi) from the territorial capital, Darwin . In 1623, Dutch East India Company captain Willem Joosten van Colster (or Coolsteerdt) sailed into the Gulf of Carpentaria and Cape Arnhem is named after his ship, the Arnhem , which itself
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#17328518310481152-455: Is a useful concept. Tidal stage is also measured in degrees, with 360° per tidal cycle. Lines of constant tidal phase are called cotidal lines , which are analogous to contour lines of constant altitude on topographical maps , and when plotted form a cotidal map or cotidal chart . High water is reached simultaneously along the cotidal lines extending from the coast out into the ocean, and cotidal lines (and hence tidal phases) advance along
1248-471: Is also notable for Aboriginal rock art , some examples of which can be found at Ubirr Rock , Injalak Hill , and in the Canon Hill area. Some of these record the early years of European explorers and settlers, sometimes in such detail that Martini–Henry rifles can be identified. They also depict axes, and detailed paintings of aircraft and ships. One remote shelter, several hundred kilometres from Darwin, has
1344-422: Is at once cotidal with high and low waters, which is satisfied by zero tidal motion. (The rare exception occurs when the tide encircles an island, as it does around New Zealand, Iceland and Madagascar .) Tidal motion generally lessens moving away from continental coasts, so that crossing the cotidal lines are contours of constant amplitude (half the distance between high and low water) which decrease to zero at
1440-461: Is highly prized in Chinese cuisine, for folk medicine, and as an aphrodisiac . This Makassan contact with Australia is the first recorded example of interaction between the inhabitants of the Australian continent and their Asian neighbours. This contact had a major effect on local Aboriginal Australians . The Makassans exchanged goods such as cloth , tobacco , knives , rice , and alcohol for
1536-493: Is never time for the fluid to "catch up" to the state it would eventually reach if the tidal force were constant—the changing tidal force nonetheless causes rhythmic changes in sea surface height. When there are two high tides each day with different heights (and two low tides also of different heights), the pattern is called a mixed semi-diurnal tide . The changing distance separating the Moon and Earth also affects tide heights. When
1632-408: Is not necessarily when the Moon is nearest to zenith or nadir , but the period of the forcing still determines the time between high tides. Because the gravitational field created by the Moon weakens with distance from the Moon, it exerts a slightly stronger than average force on the side of the Earth facing the Moon, and a slightly weaker force on the opposite side. The Moon thus tends to "stretch"
1728-502: Is not the case due to the free fall of the whole Earth, not only the oceans, towards these bodies) a different pattern of tidal forces would be observed, e.g. with a much stronger influence from the Sun than from the Moon: The solar gravitational force on the Earth is on average 179 times stronger than the lunar, but because the Sun is on average 389 times farther from the Earth, its field gradient
1824-502: Is one of the oldest living cultures on Earth, at around 60,000 years old. DNA studies have confirmed that " Aboriginal Australians are one of the oldest living populations in the world, certainly the oldest outside of Africa"; their descendants left the African continent 75,000 years ago. They may have the oldest continuous culture on earth. Oral histories comprising complex narratives have been passed down through hundreds of generations, and
1920-715: Is part of the Nitmiluk Agreement, which aims at building economic opportunities for Aboriginal people in the fishing industry, including establishing an Aboriginal-owned fishing enterprise. The Garrangali Band , from the tiny community of Baniyala on the bay, in their 2020 song "One Voice", sing of the way of life in the region. Mudiny Guyula, the band's lead vocalist , said that the song is about bringing people “back to their promised land, their homeland, so we can recognise who we are”. 13°07′59″S 136°00′55″E / 13.133°S 136.015167°E / -13.133; 136.015167 Arnhem Land Arnhem Land
2016-402: Is shorter than average, and stronger tidal currents than average. Neaps result in less extreme tidal conditions. There is about a seven-day interval between springs and neaps. Tidal constituents are the net result of multiple influences impacting tidal changes over certain periods of time. Primary constituents include the Earth's rotation, the position of the Moon and Sun relative to the Earth,
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#17328518310482112-419: Is the time required for the Earth to rotate once relative to the Moon. Simple tide clocks track this constituent. The lunar day is longer than the Earth day because the Moon orbits in the same direction the Earth spins. This is analogous to the minute hand on a watch crossing the hour hand at 12:00 and then again at about 1: 05 + 1 ⁄ 2 (not at 1:00). The Moon orbits the Earth in the same direction as
2208-626: The Aboriginal rock art , dated by modern techniques, shows continuity of their culture. Arnhem Land is the location of the oldest-known (as of 2010 ) stone axe of its kind, which scholars believe to be 35,500 years old. Rock art depicting what may be acts of violence between hunter-gatherers in Arnhem land has been tentatively dated to 10,000 years ago. At least since the 18th century (and probably earlier) Muslim traders from Makassar of Sulawesi visited Arnhem Land each year to trade, harvest, and process sea cucumbers or trepang . This marine animal
2304-589: The Coriolis effect , is generally clockwise in the southern hemisphere and counterclockwise in the northern hemisphere. The difference of cotidal phase from the phase of a reference tide is the epoch . The reference tide is the hypothetical constituent "equilibrium tide" on a landless Earth measured at 0° longitude, the Greenwich meridian. In the North Atlantic, because the cotidal lines circulate counterclockwise around
2400-692: The Euripus Strait and the Strait of Messina puzzled Aristotle .) Philostratus discussed tides in Book Five of The Life of Apollonius of Tyana . Philostratus mentions the moon, but attributes tides to "spirits". In Europe around 730 AD, the Venerable Bede described how the rising tide on one coast of the British Isles coincided with the fall on the other and described the time progression of high water along
2496-507: The Maung speaking Goulburn Islands (Mardbalk Arts & Crafts). Arnhem Land is also known for embracing the homeland movement, sometimes referred to as the outstation movement . For many decades prior to 1970, the East Arnhem Land Yolngu people lived on mission stations , such as Yirrkala. From April 1972, Yolngu families began moving away, back to their traditional clan lands. This was instigated by Yolngu people, before there
2592-541: The Moon (and to a much lesser extent, the Sun ) and are also caused by the Earth and Moon orbiting one another. Tide tables can be used for any given locale to find the predicted times and amplitude (or " tidal range "). The predictions are influenced by many factors including the alignment of the Sun and Moon, the phase and amplitude of the tide (pattern of tides in the deep ocean),
2688-518: The North Sea . Much later, in the late 20th century, geologists noticed tidal rhythmites , which document the occurrence of ancient tides in the geological record, notably in the Carboniferous . The tidal force produced by a massive object (Moon, hereafter) on a small particle located on or in an extensive body (Earth, hereafter) is the vector difference between the gravitational force exerted by
2784-447: The amphidromic systems of the oceans, and the shape of the coastline and near-shore bathymetry (see Timing ). They are however only predictions, the actual time and height of the tide is affected by wind and atmospheric pressure . Many shorelines experience semi-diurnal tides—two nearly equal high and low tides each day. Other locations have a diurnal tide—one high and low tide each day. A "mixed tide"—two uneven magnitude tides
2880-489: The higher low water and the lower low water . The daily inequality is not consistent and is generally small when the Moon is over the Equator . The following reference tide levels can be defined, from the highest level to the lowest: The semi-diurnal range (the difference in height between high and low waters over about half a day) varies in a two-week cycle. Approximately twice a month, around new moon and full moon when
2976-440: The lunar theory of E W Brown describing the motions of the Moon, Arthur Thomas Doodson developed and published in 1921 the first modern development of the tide-generating potential in harmonic form: Doodson distinguished 388 tidal frequencies. Some of his methods remain in use. From ancient times, tidal observation and discussion has increased in sophistication, first marking the daily recurrence, then tides' relationship to
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3072-455: The sea cucumbers were traded by the Makassans to Southern China . In 2014, an 18th-century Chinese coin was found in the remote area of Wessel Islands off the coast on a beach on Elcho Island during a historical expedition. The coin was found near previously known Makassan trepanger fishing sites where several other Dutch coins have been discovered nearby, but never a Chinese coin. The coin
3168-723: The 800 people in the Laynhapuy homelands will be forced to move to towns such as Yirrkala on the Gove Peninsula, creating new law and order problems, while those who stay will be severely disadvantaged." In response to changes made by the Northern Territory government surrounding reduced support for the homelands in 2009, the Indigenous leader Patrick Dodson criticised the Northern Territory Government's controversial new policy on remote Aboriginal communities, describing it as
3264-538: The Court made it clear that such permission is also required to go on to water overlying that land. This case is signification as it was the first time that native title rights for Indigenous Australians had been recognised over an intertidal zone . The tiny Yolŋu community of Baniyala played a key role in achieving the outcome. In 2019, the people of Baniyala engaged the CSIRO to investigate industries which could help boost
3360-426: The Earth rotates on its axis, so it takes slightly more than a day—about 24 hours and 50 minutes—for the Moon to return to the same location in the sky. During this time, it has passed overhead ( culmination ) once and underfoot once (at an hour angle of 00:00 and 12:00 respectively), so in many places the period of strongest tidal forcing is the above-mentioned, about 12 hours and 25 minutes. The moment of highest tide
3456-419: The Earth slightly along the line connecting the two bodies. The solid Earth deforms a bit, but ocean water, being fluid, is free to move much more in response to the tidal force, particularly horizontally (see equilibrium tide ). As the Earth rotates, the magnitude and direction of the tidal force at any particular point on the Earth's surface change constantly; although the ocean never reaches equilibrium—there
3552-570: The Earth's accumulated dynamic tidal response to the applied forces, which response is influenced by ocean depth, the Earth's rotation, and other factors. In 1740, the Académie Royale des Sciences in Paris offered a prize for the best theoretical essay on tides. Daniel Bernoulli , Leonhard Euler , Colin Maclaurin and Antoine Cavalleri shared the prize. Maclaurin used Newton's theory to show that
3648-652: The IBA is 45,811 ha. It supports globally important numbers of magpie geese (up to 500,000 individuals), wandering whistling-ducks (up to 40,000), and brolgas (up to 3000). Many other waterbirds breed in colonies on the floodplain, especially egrets , herons and spoonbills , while the mudflats are used by flocks of migratory waders in summer. Wader species using the site in large numbers include black-tailed godwits , lesser sand plovers and red-necked stints . The islands hold significant breeding colonies of little , black-naped and bridled terns . The beaches of
3744-427: The Moon and its phases. Bede starts by noting that the tides rise and fall 4/5 of an hour later each day, just as the Moon rises and sets 4/5 of an hour later. He goes on to emphasise that in two lunar months (59 days) the Moon circles the Earth 57 times and there are 114 tides. Bede then observes that the height of tides varies over the month. Increasing tides are called malinae and decreasing tides ledones and that
3840-626: The Moon is at first quarter or third quarter, the Sun and Moon are separated by 90° when viewed from the Earth (in quadrature ), and the solar tidal force partially cancels the Moon's tidal force. At these points in the lunar cycle, the tide's range is at its minimum; this is called the neap tide , or neaps . "Neap" is an Anglo-Saxon word meaning "without the power", as in forðganges nip (forth-going without-the-power). Neap tides are sometimes referred to as quadrature tides . Spring tides result in high waters that are higher than average, low waters that are lower than average, " slack water " time that
3936-459: The Moon is closest, at perigee , the range increases, and when it is at apogee , the range shrinks. Six or eight times a year perigee coincides with either a new or full moon causing perigean spring tides with the largest tidal range . The difference between the height of a tide at perigean spring tide and the spring tide when the moon is at apogee depends on location but can be large as a foot higher. These include solar gravitational effects,
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4032-462: The Moon on the particle, and the gravitational force that would be exerted on the particle if it were located at the Earth's center of mass. Whereas the gravitational force subjected by a celestial body on Earth varies inversely as the square of its distance to the Earth, the maximal tidal force varies inversely as, approximately, the cube of this distance. If the tidal force caused by each body were instead equal to its full gravitational force (which
4128-457: The Moon's altitude (elevation) above the Earth's Equator, and bathymetry . Variations with periods of less than half a day are called harmonic constituents . Conversely, cycles of days, months, or years are referred to as long period constituents. Tidal forces affect the entire earth , but the movement of solid Earth occurs by mere centimeters. In contrast, the atmosphere is much more fluid and compressible so its surface moves by kilometers, in
4224-449: The Moon. Abu Ma'shar discussed the effects of wind and Moon's phases relative to the Sun on the tides. In the 12th century, al-Bitruji (d. circa 1204) contributed the notion that the tides were caused by the general circulation of the heavens. Simon Stevin , in his 1608 De spiegheling der Ebbenvloet ( The theory of ebb and flood ), dismissed a large number of misconceptions that still existed about ebb and flood. Stevin pleaded for
4320-537: The Northern Territory's coastline have exclusive rights over commercial and recreational fishing in tidal waters overlying their land. The bay is about 90 km in length and up to 35 km in width. Its 45 km wide mouth stretches from Cape Shield in the north-east to Cape Barrow in the south-west, with Woodah Island in between. It has a diverse inner coastline of many small bays, inlets, headlands and islands, bordered by intertidal mudflats and mangroves merging into freshwater floodplains . The bay and
4416-593: The Northern Territory's gross state product, mainly through bauxite mining . In 2019, it was announced that NASA had chosen Arnhem Land as the location for a space launch facility , the Arnhem Space Centre . On 27 June 2022, NASA launched the first rocket there, the first rocket launch from a commercial spaceport outside the US, and two further launches followed within weeks. The Yolŋu culture in East Arnhem Land
4512-400: The Northern Territory's gross state product, mainly through bauxite mining. In 2019, it was announced that NASA had chosen Arnhem Land as the location for a space launch facility. The Arnhem Space Centre was built near Nhulunbuy, employing mostly local labour, and on 27 June 2022, NASA launched the first rocket there, which was the first rocket launch from a commercial spaceport outside
4608-663: The Northumbrian coast. The first tide table in China was recorded in 1056 AD primarily for visitors wishing to see the famous tidal bore in the Qiantang River . The first known British tide table is thought to be that of John Wallingford, who died Abbot of St. Albans in 1213, based on high water occurring 48 minutes later each day, and three hours earlier at the Thames mouth than upriver at London . In 1614 Claude d'Abbeville published
4704-518: The Sun and moon. Pytheas travelled to the British Isles about 325 BC and seems to be the first to have related spring tides to the phase of the moon. In the 2nd century BC, the Hellenistic astronomer Seleucus of Seleucia correctly described the phenomenon of tides in order to support his heliocentric theory. He correctly theorized that tides were caused by the moon , although he believed that
4800-420: The Sun, Moon, and Earth form a line (a configuration known as a syzygy ), the tidal force due to the Sun reinforces that due to the Moon. The tide's range is then at its maximum; this is called the spring tide . It is not named after the season , but, like that word, derives from the meaning "jump, burst forth, rise", as in a natural spring . Spring tides are sometimes referred to as syzygy tides . When
4896-517: The Two Chief World Systems , whose working title was Dialogue on the Tides , gave an explanation of the tides. The resulting theory, however, was incorrect as he attributed the tides to the sloshing of water caused by the Earth's movement around the Sun. He hoped to provide mechanical proof of the Earth's movement. The value of his tidal theory is disputed. Galileo rejected Kepler's explanation of
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#17328518310484992-518: The US. Two further launches followed, the third on 11 July. Other space companies are interested in using the rocket launch pad, and NASA confirmed that it will use the facility again in the future. The 2006 film Ten Canoes captures life in Arnhem Land through a story tapping into the Aboriginal mythic past; it was co-directed by one of the indigenous cast members. The film and the documentary about
5088-559: The adjoining floodplains are held by the Arnhem Land Aboriginal Land Trust as Aboriginal freehold land. The waters of the bay are used for commercial and recreational fishing, especially for mud crabs . The northern part of the bay and its surrounds are part of the Laynhapuy Indigenous Protected Area , which is planned to be extended to include the remainder of the coastal waters and islands of
5184-423: The amphidromic point, the high tide passes New York Harbor approximately an hour ahead of Norfolk Harbor. South of Cape Hatteras the tidal forces are more complex, and cannot be predicted reliably based on the North Atlantic cotidal lines. Investigation into tidal physics was important in the early development of celestial mechanics , with the existence of two daily tides being explained by the Moon's gravity. Later
5280-429: The amphidromic point. For a semi-diurnal tide the amphidromic point can be thought of roughly like the center of a clock face, with the hour hand pointing in the direction of the high water cotidal line, which is directly opposite the low water cotidal line. High water rotates about the amphidromic point once every 12 hours in the direction of rising cotidal lines, and away from ebbing cotidal lines. This rotation, caused by
5376-530: The atmosphere which did not include rotation. In 1770 James Cook 's barque HMS Endeavour grounded on the Great Barrier Reef . Attempts were made to refloat her on the following tide which failed, but the tide after that lifted her clear with ease. Whilst she was being repaired in the mouth of the Endeavour River Cook observed the tides over a period of seven weeks. At neap tides both tides in
5472-443: The bay's larger islands are important for nesting flatback sea turtles . There is a large colony of little red flying foxes in the mangroves at the northern end of the bay. The threatened brush-tailed rabbit rat is present. Douglas' skink ( Glaphyromorphus douglasi ) is endemic to the Northern Territory. Introduced water buffalos and feral pigs threaten the wetlands. The Blue Mud Bay case , or Blue Mud sea rights case ,
5568-465: The bay. Triumfetta litticola , a plant species endemic to the Arnhem Coast bioregion, has been recorded. The threatened Australian arenga palm ( Arenga australasica ) is also found here, as well as 34 plant species endemic to the Northern Territory . The bay's seasonally flooded coastal plains have been classified by BirdLife International as an Important Bird Area (IBA). The area covered by
5664-427: The best elements of their homelands. Indigenous tourism ventures incorporating the controlled use of homelands are now showing signs of success for a select number of Yolngu. 12°43′48″S 134°35′24″E / 12.73000°S 134.59000°E / -12.73000; 134.59000 Tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by
5760-410: The coast. Semi-diurnal and long phase constituents are measured from high water, diurnal from maximum flood tide. This and the discussion that follows is precisely true only for a single tidal constituent. For an ocean in the shape of a circular basin enclosed by a coastline, the cotidal lines point radially inward and must eventually meet at a common point, the amphidromic point . The amphidromic point
5856-579: The coasts of northern Australia. In Arnhem Land, the word is still widely used today to refer to white Australians. The Dutch started settling in Sulawesi Island in the early 17th century. Archaeological remains of Makassar contact, including trepang processing plants (drying, smoking) from the 18th and 19th centuries, are still found at Australian locations such as Port Essington and Groote Eylandt . The Makassans also planted tamarind trees (native to Madagascar and East Africa ). After processing,
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#17328518310485952-475: The daily tides were explained more precisely by the interaction of the Moon's and the Sun's gravity. Seleucus of Seleucia theorized around 150 BC that tides were caused by the Moon. The influence of the Moon on bodies of water was also mentioned in Ptolemy 's Tetrabiblos . In De temporum ratione ( The Reckoning of Time ) of 725 Bede linked semidurnal tides and the phenomenon of varying tidal heights to
6048-478: The dry season (April to September) to daily highs of 33 °C (91 °F) in the wet season (October to March). In 1931, an area of 96,000 km (37,000 sq mi) was proclaimed as an Aboriginal reserve , named Arnhem Land Aboriginal Reserve. As of 2007 the Land Trust held about 100,000 km (39,000 sq mi) as Aboriginal freehold land (with the exception of mining leases); it remains one of
6144-470: The early 1970s as a mining town for bauxite . Other major population centres are Yirrkala (just outside Nhulunbuy), Gunbalanya (formerly Oenpelli), Ramingining , and Maningrida . A substantial proportion of the population, which is mostly Aboriginal , lives on small outstations or homelands. This outstation movement started in the early 1980s. Many Aboriginal groups moved to usually very small settlements on their traditional lands , often to escape
6240-439: The early 21st century, a focus governments about the "viability" of the homelands has caused tensions and uncertainty within the Arnhem Land community. In September 2008, then Darwin correspondent for The Age , Lindsay Murdoch, wrote: "Elders tell of their fears that Yolngu culture and society will not survive if clans cannot continue to live on and access their land through homelands. They warn that if services are cut, many of
6336-439: The far north-east, on the Gove Peninsula. Gove is the site of large-scale bauxite mining with an associated alumina refinery. Its administrative centre is the town of Nhulunbuy, the fourth-largest population centre in the Northern Territory. The climate of Arnhem Land is tropical monsoon with a wet and dry season. The temperature has little seasonal variation; however, it can range from overnight lows of 15 °C (59 °F) in
6432-531: The first to map co-tidal lines, for Great Britain, Ireland and adjacent coasts, in 1840. William Whewell expanded this work ending with a nearly global chart in 1836. In order to make these maps consistent, he hypothesized the existence of a region with no tidal rise or fall where co-tidal lines meet in the mid-ocean. The existence of such an amphidromic point , as they are now known, was confirmed in 1840 by Captain William Hewett, RN , from careful soundings in
6528-584: The history and culture of Yolngu people, was filmed in Arnhem land. The Aboriginal community of Yirrkala , just outside Nhulunbuy, is internationally known for bark paintings , promoting the rights of Indigenous Australians , and as the origin of the yidaki , or didgeridoo . The community of Gunbalanya (previously known as Oenpelli ) in Western Arnhem Land is also notable for bark painting. The indigenous inhabitants also create temporary sand sculptures as part of their sacred rituals. Arnhem Land
6624-415: The idea that the attraction of the Moon was responsible for the tides and spoke in clear terms about ebb, flood, spring tide and neap tide , stressing that further research needed to be made. In 1609 Johannes Kepler also correctly suggested that the gravitation of the Moon caused the tides, which he based upon ancient observations and correlations. Galileo Galilei in his 1632 Dialogue Concerning
6720-464: The interaction was mediated by the pneuma . He noted that tides varied in time and strength in different parts of the world. According to Strabo (1.1.9), Seleucus was the first to link tides to the lunar attraction, and that the height of the tides depends on the moon's position relative to the Sun. The Naturalis Historia of Pliny the Elder collates many tidal observations, e.g., the spring tides are
6816-523: The largest parcels of Aboriginal-owned land in Australia and is perhaps best known for its isolation, the art of its people, and the strong continuing traditions of its Aboriginal inhabitants. Arnhem Land is composed of many different Aboriginal countries and language groups . North-east Arnhem Land is home to the Yolngu people, one of the largest Indigenous groups in Australia, who have succeeded in maintaining
6912-411: The largest source of short-term sea-level fluctuations, sea levels are also subject to change from thermal expansion , wind, and barometric pressure changes, resulting in storm surges , especially in shallow seas and near coasts. Tidal phenomena are not limited to the oceans, but can occur in other systems whenever a gravitational field that varies in time and space is present. For example, the shape of
7008-1078: The layout of the Makassan praus used for trepang (sea cucumber) fishing in the area. This was a legacy of Yolngu trade links with the people on the Indonesian island of Sulawesi . The trading relationship antedated European settlement by some 200 years. Aboriginal artists in Arnhem Land are primarily represented by Aboriginal Art Centres , nonprofit, community-owned organisations. In East Arnhem Land, primarily Yolngu Matha -speaking artists are promoted by Buku-Larrnggay Mulka in Yirrkala, Bula'bula Arts in Ramingining , Elcho Island Arts and Crafts on Elcho Island , Gapuwiyak Culture and Arts in Gapuwiyak and Milingimbi Art and Culture on Milingimbi Island . In Central Arnhem Land, Maningrida Arts & Culture in Maningrida promotes
7104-492: The local economy, including the potential for aquaculture (in particular sea cucumbers ), mining, forestry, eco-tourism , and chartered fishing expeditions. In July 2019, Northern Land Council entered into an agreement with the NT Government for rights over access to the waters for commercial and recreational fishing , before consulting the appropriate traditional owners. After community leader Djambawa Marawili raised
7200-458: The making of the film, The Balanda and the Bark Canoes , give a remarkable testimony to the indigenous struggle to keep their culture alive – or rather revive it in the wake of considerable relative modernisation and influence of white ( balanda ) cultural imposition. High Ground (2020 film) , a 2020 feature film directed by Stephen Maxwell Johnson , based on historical fact and reflecting
7296-590: The matter, a meeting was held with the NLC, and on the 11th anniversary of the High Court's Blue Mud Bay decision, traditional owners signed an agreement to allow fishing access to these waters for the following 18 months. In July 2020, the Northern Land Council and the NT Government signed the "Blue Mud Bay Action Plan", by which both are committed to securing fishing rights for the region's Indigenous people. This plan
7392-419: The moments of slack tide differ significantly from those of high and low water. Tides are commonly semi-diurnal (two high waters and two low waters each day), or diurnal (one tidal cycle per day). The two high waters on a given day are typically not the same height (the daily inequality); these are the higher high water and the lower high water in tide tables . Similarly, the two low waters each day are
7488-412: The month is divided into four parts of seven or eight days with alternating malinae and ledones . In the same passage he also notes the effect of winds to hold back tides. Bede also records that the time of tides varies from place to place. To the north of Bede's location ( Monkwearmouth ) the tides are earlier, to the south later. He explains that the tide "deserts these shores in order to be able all
7584-514: The more to be able to flood other [shores] when it arrives there" noting that "the Moon which signals the rise of tide here, signals its retreat in other regions far from this quarter of the heavens". Later medieval understanding of the tides was primarily based on works of Muslim astronomers , which became available through Latin translation starting from the 12th century. Abu Ma'shar al-Balkhi (d. circa 886), in his Introductorium in astronomiam , taught that ebb and flood tides were caused by
7680-420: The obliquity (tilt) of the Earth's Equator and rotational axis, the inclination of the plane of the lunar orbit and the elliptical shape of the Earth's orbit of the Sun. A compound tide (or overtide) results from the shallow-water interaction of its two parent waves. Because the M 2 tidal constituent dominates in most locations, the stage or phase of a tide, denoted by the time in hours after high water,
7776-408: The problem from the perspective of a static system (equilibrium theory), that provided an approximation that described the tides that would occur in a non-inertial ocean evenly covering the whole Earth. The tide-generating force (or its corresponding potential ) is still relevant to tidal theory, but as an intermediate quantity (forcing function) rather than as a final result; theory must also consider
7872-498: The problems of the larger towns. These population groups have very little Western cultural influence, and Arnhem Land is arguably one of the last areas in Australia that could be seen as a completely separate country. Many of the region's leaders have called and continue to call for a treaty that would allow the Yolŋu to operate under their own traditional laws . In 2013–14, the entire region contributed around A$ 1.3 billion or 7 percent to
7968-545: The property rights of much of Arnhem Land were held by the Eastern and African Cold Storage Supply Company . This Anglo-Australian consortium leased the region under the name of Arafura cattle station and attempted to construct a massive cattle raising and meat production industry. The company employed roving gangs of armed men to shoot the resident Aboriginal population. In 1971, the Gove land rights case ( Milirrpum v Nabalco Pty Ltd )
8064-527: The property, Jim Randell, bolted a swivel cannon to the verandah of the homestead to keep the Indigenous people away, while Jack Watson , the last manager of the property, reportedly "wiped out a lot" of "the blacks" living on the coast at Blue Mud Bay . During the period of Watson's management, another large massacre is recorded to have happened at Mirki on the north coast of Florida Station. The Yolngu people today remember this massacre where many people including children were shot dead. From 1903 to 1908,
8160-415: The right to trepang coastal waters and employ local labour. Makassar pidgin became a lingua franca along the north coast among several indigenous Australian groups who were brought into greater contact with each other by the seafaring Makassan culture. These traders from the southwest corner of Sulawesi also introduced the word balanda for white people, long before western explorers set foot on
8256-445: The sense of the contour level of a particular low pressure in the outer atmosphere. In most locations, the largest constituent is the principal lunar semi-diurnal , also known as the M2 tidal constituent or M 2 tidal constituent . Its period is about 12 hours and 25.2 minutes, exactly half a tidal lunar day , which is the average time separating one lunar zenith from the next, and thus
8352-500: The solid part of the Earth is affected slightly by Earth tide , though this is not as easily seen as the water tidal movements. Four stages in the tidal cycle are named: Oscillating currents produced by tides are known as tidal streams or tidal currents . The moment that the tidal current ceases is called slack water or slack tide . The tide then reverses direction and is said to be turning. Slack water usually occurs near high water and low water, but there are locations where
8448-489: The tides. Isaac Newton (1642–1727) was the first person to explain tides as the product of the gravitational attraction of astronomical masses. His explanation of the tides (and many other phenomena) was published in the Principia (1687) and used his theory of universal gravitation to explain the lunar and solar attractions as the origin of the tide-generating forces. Newton and others before Pierre-Simon Laplace worked
8544-475: The work " Histoire de la mission de pères capucins en l'Isle de Maragnan et terres circonvoisines ", where he exposed that the Tupinambá people already had an understanding of the relation between the Moon and the tides before Europe. William Thomson (Lord Kelvin) led the first systematic harmonic analysis of tidal records starting in 1867. The main result was the building of a tide-predicting machine using
8640-630: The work of a diverse range of Kuninjku , Burarra , and Gurrgoni artists, amongst others. In West Arnhem Land, Injalak Arts in Gunbalanya represents mainly Kunwinjku artists. Ngukurr Arts is located on the Roper River in Southern Arnhem Land. Art is also produced on the many islands of Arnhem Land, and there are art centres on the Anindilyakwa speaking Groote Eylandt (Anindilyakwa Art) and
8736-429: Was established to assist the homelands. Homelands are tiny communities where members of related clan groups live on their traditional land, living according to Yolngu rom (law) . There are benefits to the people to be living in these homelands, including: Homelands also reduce pressure on other Indigenous communities, which are already suffering from problems in the housing, health and education services areas. In
8832-480: Was government support for the outstation movement. The people cleared land for airstrips and built their own houses from local timber, with the help of non-Indigenous people from the mission. The elders of the clans aimed to determine their own futures, basing their societies on Yolngu law, while living and raising their children on their lands in a sustainable and self-sufficient way. In 1985, Laynhapuy Homelands Aboriginal Corporation (LHAC), an Aboriginal corporation ,
8928-468: Was named after the city of Arnhem in the Netherlands. The area covers about 97,000 km (37,000 sq mi) and has an estimated population of 16,000, of whom 12,000 are Aboriginal and Torres Strait Islander people . Two regions are often distinguished as East Arnhem ( Land ) and West Arnhem ( Land ). The region's service hub is Nhulunbuy , 600 km (370 mi) east of Darwin, set up in
9024-565: Was probably made in Beijing around 1735. In 1884, 10,000 square miles of Arnhem Land was sold by the colonial British government to cattle grazier , John Arthur Macartney . The property was called Florida Station and Macartney stocked it with cattle overlanded from Queensland. Monsoonal flooding, disease and strong resistance from the local Aboriginal population resulted in Florida Station being abandoned by Macartney in 1893. The first manager of
9120-666: Was the first litigation on native title in Australia , and the first significant legal case for Aboriginal land rights in Australia . The area is from Port Roper on the Gulf of Carpentaria around the coast to the East Alligator River , where it adjoins Kakadu National Park . The major centres are Jabiru on the Kakadu National Park border, Maningrida at the Liverpool River mouth, and Nhulunbuy (also known as Gove) in
9216-662: Was the name given to a court case with original reference to the ownership of fishing rights in tidal waters overlying Aboriginal land at Blue Mud Bay. The case was eventually decided by the High Court of Australia on 23 July 2008 when it ruled on an appeal made by the Northern Territory Government , the Commonwealth of Australia and the Northern Territory Seafood Council against a decision made by
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