77-560: Port Stephens , an open youthful tide-dominated drowned-valley estuary , is a large natural harbour of approximately 134 square kilometres (52 sq mi) located in the Hunter and Mid North Coast regions of New South Wales , Australia . Port Stephens lies within the Port Stephens–Great Lakes Marine Park and is situated about 160 kilometres (99 mi) north-east of Sydney . The harbour lies wholly within
154-445: A diurnal tide—one high and low tide each day. A "mixed tide"—two uneven magnitude tides 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
231-677: 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
308-512: 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
385-496: 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 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
462-447: A gravitational field that varies in time and space is present. For example, the shape of 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
539-751: A population of 857, is at the north-western corner of the port, at the mouth of the Karuah River. East of the Karuah River, in the Mid-Coast Council local government area there are 3,584 people living in Bundabah , Carrington , Hawks Nest , North Arm Cove , Pindimar, Tahlee and Tea Gardens. Port Stephens is a popular tourism destination with a strong focus on aquatic activities such as whale and dolphin watching, fishing and recreational boating and swimming. [REDACTED] Media related to Port Stephens (Estuary) at Wikimedia Commons Tide Tides are
616-464: 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
693-514: 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
770-455: 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
847-422: 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
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#1732859164853924-418: 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 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
1001-454: 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 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
1078-462: Is larger than Sydney Harbour . Port Stephens extends approximately 24 km (15 mi) inland from the Tasman Sea and at its widest point, between Tanilba Bay and Tahlee , it is 6.5 km (4 mi) across. The narrowest point is between Soldiers Point and Pindimar where the distance is only 1.1 km (0.7 mi). Between Nelson Bay and Tea Gardens , in the most well known section of
1155-519: Is located at the north-western corner of Port Stephens into which the Karuah River feeds. According to the 2016 census , there 1,411 people in Karuah. The largest settlement within the locality is the village of Karuah, which is on the old Pacific Highway and straddles the Karuah River. Most of the village, which occupies only about 0.7 square kilometres (0.3 sq mi) of the suburb's total area of 74.7 km (28.8 sq mi), lies within
1232-446: 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
1309-408: 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"
1386-456: 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
1463-402: 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,
1540-536: Is split between the Port Stephens and Mid-Coast councils with most (approximately 51%) located in the Port Stephens Council area. The village of Karuah is also split between the two councils with almost all of the village located in Port Stephens Council. The Karuah River , which runs approximately north to south through the centre of Karuah, forms the border between the two councils within the locality. Karuah
1617-419: 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
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#17328591648531694-678: Is weaker. The overall proportionality is Karuah, New South Wales Karuah is a locality in both the Port Stephens and Mid-Coast Councils , the Port Stephens lga side is part the Hunter Region while the Mid-Coast lga is in the Mid North Coast region of New South Wales , Australia. It is thought that the name means 'native plum tree' in the local Aboriginal dialect. In 1790, five convicts escaped from Sydney and relocated to
1771-589: 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
1848-692: 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
1925-751: The Myall and Karuah rivers, Tilligerry Creek, and the Tasman Sea of the South Pacific Ocean . The lower port has a predominantly marine ecology and the upper port an estuarine ecology. The area to the east of Port Stephens comprises the Tomago/Tomaree/Stockton sand beds. A narrow entrance between two striking hills of volcanic origin marks the opening of Port Stephens to the sea. The southern headland, Tomaree or South Head, rises to 161 metres (528 ft) above mean sea level (AMSL) while Yacaaba ,
2002-518: 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
2079-417: The local government area of Port Stephens ; although its northern shoreline forms the boundary between the Port Stephens and MidCoast local government areas. According to the 2006 census , more than 26,000 people lived within 3 km (1.9 mi) of its 113 km (70 mi) long shoreline and more than 32,000 lived within 10 km (6 mi). Port Stephens is formed through the confluence of
2156-440: 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
2233-426: 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
2310-419: 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
2387-570: 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
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2464-427: 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
2541-459: 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,
2618-462: 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
2695-457: 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
2772-449: 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
2849-449: 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
2926-663: 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
3003-709: The Port Stephens LGA . It includes the largest Aboriginal community in the Port Stephens LGA and, at the 2006 Census, had a population of approximately 857. The rest of the suburb's population live in the rural properties which surround the village. The Karuah bridge was built and opened in December 1957. In 2004, the Karuah Bypass was opened which, as part of the AusLink program, speeds up car and truck travel times past
3080-450: The Sun and Moon, the phase and amplitude of the tide (pattern of tides in the deep ocean), 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
3157-518: 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
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3234-523: The Tomaree and Tilligerry peninsulas. These are separated by Tilligerry Creek, a watercourse covering approximately 7.7 km (3.0 sq mi), which drains the land in the low-lying areas of Salt Ash , Bobs Farm , Tanilba Bay and Mallabula . While the Tilligerry Peninsula is geographically closer to major centres such as Sydney and Newcastle , it lacks the urban development that has occurred on
3311-517: 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
3388-423: 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
3465-429: 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
3542-514: The area. In 1795 the crew of HMS Providence discovered a group of escaped convicts living with the Worimi people . Port Stephens became a popular haven for escaped convicts and so in 1820 a garrison of soldiers was established at what is now known as Soldiers Point. The 63- tonne (62- long-ton ) cutter Lambton , commanded by Captain James Corlette, began shipping timber and wool out of
3619-525: The area. In 1795 the Karuah River was first surveyed as part of a wider survey of Port Stephens. In 1811 Governor Lachlan Macquarie decided to name the area the Clyde. By 1816 permits were issued to allow cedar cutting in the area. In 1824 the Australian Agricultural Company purchased a million acres to create the township. In 1907 the name was changed from Sawyers Point to Karuah. Karuah
3696-530: 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
3773-410: 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
3850-565: The conservation of the threatened Gould's petrel , and with no public access. The Worimi are the traditional owners for the area which is now called Port Stephens and the wider region is home to numerous sites of deep cultural significance to the Worimi. The port was named by Captain Cook when he passed by on 11 May 1770, honouring Sir Philip Stephens , who was Secretary to the Admiralty . Stephens
3927-475: 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
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#17328591648534004-531: 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
4081-420: 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 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
4158-415: 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
4235-569: The increasing popularity of coastal retirement lifestyles, there has been major expansion of these towns. On 1 December 2005 the Port Stephens–Great Lakes Marine Park was established pursuant to the Marine Parks Act, 1997 (NSW). The park comprises approximately 97,200 hectares (240,000 acres) and includes all of Port Stephens, the Karuah and Myall rivers and all their creeks and tributaries under tidal influence. The park
4312-464: 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
4389-412: 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
4466-514: 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
4543-519: The much larger (25 km (10 sq mi) vs 115 km (44 sq mi) respectively) Tomaree peninsula. Although Lemon Tree Passage, on the Tilligerry Peninsula, and Soldiers Point, on the Tomaree Peninsula, are only 2.9 km (1.8 mi) from each other, physical separation of the suburbs by Port Stephens and Tilligerry Creek results in them being almost 40 km (25 mi) from each other by road. The town of Karuah , located at
4620-424: The north-western corner of the port near the mouth of the Karuah River, experiences similar geographical separation from the Tilligerry Peninsula. Despite being only 7.7 km (4.8 mi) from Tanilba Bay, the road distance between the two suburbs is 40 km (25 mi). The western shore and the western part of the northern shore of the port are largely undeveloped with the flora ranging from scrubland in
4697-581: The northern headland, is 210 m (690 ft) AMSL. The harbour is mostly shallow and sandy but contains sufficient deep water to accommodate large vessels. After its recovery from the wreck site in 1974 the bow of the MV ; Sygna , a 53,000 tonnes (52,163 long tons ) Norwegian bulk carrier that was shipwrecked on Stockton Beach earlier that year, was moored in Port Stephens, at Salamander Bay , for almost two years. With an area of approximately 134 square kilometres (52 sq mi), Port Stephens
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#17328591648534774-420: 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,
4851-502: The port in 1816. The suburb of Corlette was named after the captain. Port Stephens has rather poor soil for the most part, and has limited agricultural potential. For this reason, no large towns developed there historically and it was never developed as a significant port. The major city and port of Newcastle developed at the mouth of the Hunter River , about 45 km (28 mi) south-west of Port Stephens. Despite this, in 1920 there
4928-437: The port in the suburbs of Corlette , Lemon Tree Passage , Mallabula, Nelson Bay, Oyster Cove , Salamander Bay, Shoal Bay , Soldiers Point, Tanilba Bay and Taylors Beach . Another 5,343 people live in other suburbs on the Tomaree peninsula that are within 10 km (6 mi) of Port Stephens. These suburbs include Anna Bay , Boat Harbour , Bobs Farm, Fingal Bay , Fishermans Bay and One Mile . Most urban development to
5005-462: The port, it is 3.8 km (2.4 mi) wide. The Karuah River drains into Port Stephens at its north-western corner. The Myall River (through the Myall Lakes ) drains into the port on its northern shore, about 5.7 km (3.5 mi) from the mouth of the port. Twelve Mile Creek drains into the port's south-western corner. The southern shore of the port is divided into two distinct areas known as
5082-408: 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
5159-412: The reference (or datum) level usually called mean sea level . While tides are usually 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
5236-592: The remoteness and lack of any significant civilian population led to the Royal Australian Navy establishing HMAS Assault , an amphibious landing training establishment, at Nelson Bay. The sick bay from HMAS Assault still stands and is used by the Port Stephens Community Arts Centre. A number of small towns developed around the port as fishing, holiday and retirement communities. Since the 1970s, with improved road access from Sydney, and
5313-553: The rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by 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
5390-445: 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
5467-400: The south of Port Stephens has occurred on the Tomaree peninsula in the suburbs of Corlette, Nelson Bay, Salamander Bay, Shoal Bay and Soldiers Point. On the western shore is the suburb of Swan Bay , a small community of around 100 persons. The main industry in the area is oyster farming, however a small tourist resort is located near the mouth of Twelve Mile Creek. Karuah township, which has
5544-489: 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
5621-532: The west to the large tracts of bushland which are present along most of the northern shore. Closer to the mouth of the port, at and near Winda Woppa , sandy beaches are prevalent. These extend from Jimmys Beach, near the mouth of the port, to the mouth of the Myall River, a distance of approximately 5.2 km (3.2 mi). Just outside the mouth of the port lie the two small insular nature reserves of Cabbage Tree Island and Boondelbah Island , both dedicated to
5698-475: 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
5775-533: Was a personal friend of Cook and had recommended him for command of the voyage. It seems Cook's initial choice had actually been Point Keppel and Keppel Bay, but instead he used Keppel Bay later. The first ship to enter the port was the Salamander , a ship of the Third Fleet that later gave the suburb of Salamander Bay its name, in 1791. In that same year escaped convicts, then known as 'bolters', discovered coal in
5852-523: Was a push for Port Stephens to be the capital city of a new state in a proposal originating from the country newspaper The Daily Observer . The proposal was the Observer' s editor Victor Thompson 's idea in response to continuing rural Australian antipathy at the Sydney-centralised funding and governance that many rural newspapers claimed had neglected to aid rural Australian towns. During World War II,
5929-437: Was established to protect the wide variety of sea life that inhabit the port and nearby coastal areas of the Tasman Sea from just south of Forster to the northern end of Stockton Beach . At the time of the 2006 census , more than 85% of the population around Port Stephens resided in towns and suburbs that have developed on or near the southern shores of the port. More than 22,188 people live within 3 km (1.9 mi) of
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