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49-530: The Hawaiian Trough , otherwise known as the Hawaiian Deep , is a moat -like depression of the seafloor surrounding the Hawaiian Islands . The weight from the volcanic island chain depresses the plastic lithosphere that is already weakened by the underlying thermal hotspot , causing subsidence to occur. The location with the greatest rate of subsidence is directly above the hotspot with

98-525: A fortification . The tower was often rectangular with four wheels with its height roughly equal to that of the wall or sometimes higher to allow archers or crossbowmen to stand on top of the tower and shoot arrows or quarrels into the fortification. Because the towers were wooden and thus flammable, they had to have some non-flammable covering of iron or fresh animal skins. Evidence for use of siege towers in Ancient Egypt and Anatolia dates to

147-465: A basic method of pest control in bonsai , a moat may be used to restrict access of crawling insects to the bonsai. [REDACTED] Media related to Moats at Wikimedia Commons Siege tower A Roman siege tower or breaching tower (or in the Middle Ages , a belfry ) is a specialized siege engine , constructed to protect assailants and ladders while approaching the defensive walls of

196-665: A combination of ramparts and moats, called Iya, used as a defence of the capital Benin City in present-day Edo State of Nigeria. It was considered the largest man-made structure lengthwise, second only to the Great Wall of China and the largest earthwork in the world. Recent work by Patrick Darling has established it as the largest man-made structure in the world, larger than Sungbo's Eredo , also in Nigeria. It enclosed 6,500 km (2,500 sq mi) of community lands. Its length

245-657: A key element used in French Classicism and Beaux-Arts architecture dwellings, both as decorative designs and to provide discreet access for service. Excellent examples of these can be found in Newport, Rhode Island at Miramar (mansion) and The Elms , as well as at Carolands , outside of San Francisco, California, and at Union Station in Toronto , Ontario, Canada. Additionally, a dry moat can allow light and fresh air to reach basement workspaces, as for example at

294-455: A layer of landslide debris. This layer contributes to the bulk of the sediment in the Trough. In the fourth and final stage, volcanic activity and subsistence effectively ends, and sediment deposits brought by turbidity currents, create a ponded unit in the deepest part of the Trough. This top layer is primary composed of turbidite and pelagic sediments. The largest mass wasting events, such as

343-546: A rate of about 0.1 inches (2.5 millimeters) per year. The Hawaiian Trough is about 18,045 feet (5,500 meters) deep and has a radius of about 8.7 miles (14.0 km). The subsiding lithosphere is balanced out and through the concept of isostasy a part of the crust surrounding the trough is levered upwards creating the Hawaiian Arch. The Hawaiian Arch extends about 656 feet (200 meters) above the surrounding ocean floor, and contains tilted coral reefs . The Hawaiian Trough

392-520: A similar role in the gunpowder age; like siege-towers, these were built out of wood on-site for mounting siege artillery . One of these was built by the Russian military engineer Ivan Vyrodkov during the siege of Kazan in 1552 (as part of the Russo-Kazan Wars ), and could hold ten large-calibre cannon and fifty lighter cannons. Likely, it was a development of the gulyay-gorod (that

441-734: A vertical outer retaining wall rising direct from the moat, is an extended usage of the ha-ha of English landscape gardening. In 2004, plans were suggested for a two-mile moat across the southern border of the Gaza Strip to prevent tunnelling from Egyptian territory to the border town of Rafah . In 2008, city officials in Yuma, Arizona planned to dig out a two-mile stretch of a 180-hectare (440-acre) wetland known as Hunters Hole to control immigrants coming from Mexico. Researchers of jumping spiders , which have excellent vision and adaptable tactics, built water-filled miniature moats, too wide for

490-669: Is a mobile fortification assembled on wagons or sleds from prefabricated wall-sized shields with holes for cannons). Later battery towers were often used by the Ukrainian Cossacks . During the Imjin War , the Japanese utilized siege towers to scale the walls of Jinju but were beaten back several times by Korean cannons . In the early 19th century, the Joseon Army utilized siege towers to lay siege to Jeonju where

539-418: Is characterized by a bedded layer of volcanoclastic material that fills the Trough as it quickly subsides due to large influxes of material from nearby volcanos. The majority of material in this layer was transported by turbidity currents that flow along the axis of the moat and transport material from mass wasting events. During the third stage, the depression fills with slumps and debris avalanches which creates

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588-469: Is filled with a stratified sedimentary section >2 km thick that was deposited in 4 sequential stages. The first (bottom) stage is a basal layer composed of 50 –100 m of primarily pelagic sediment. This layer was slowly deposited on the 80-Ma oceanic crust before the depression formed. The sediment in this layer is from a variety of different sources including wind blown material, slowly setting fine-grained sediment, and biogenic debris. The second stage

637-863: The Bronze Age . They were used extensively in warfare of the ancient Near East after the Late Bronze Age collapse , and in Egypt by Kushites from Sudan who founded the 25th dynasty . During classical antiquity they were common among Hellenistic Greek armies of the 4th century BC and later Roman armies of Europe and the Mediterranean, while also seeing use in ancient China during the Warring States Period and Han dynasty . Siege towers were of unwieldy dimensions and, like trebuchets , were therefore mostly constructed on site of

686-473: The Fall of Constantinople in 1453, Ottoman siege towers were sprayed by the defenders with Greek fire . Siege towers became vulnerable and obsolete with the development of large cannon . They had only ever existed to get assaulting troops over high walls and towers and large cannons also made high walls obsolete as fortification took a new direction. However, later constructions known as battery towers took on

735-742: The James Farley Post Office in New York City . Whilst moats are no longer a significant tool of warfare, modern architectural building design continues to use them as a defence against certain modern threats, such as terrorist attacks from car bombs and improvised fighting vehicles . For example, the new location of the Embassy of the United States in London , opened in 2018, includes a moat among its security features -

784-749: The Mississippian culture as the outer defence of some fortified villages. The remains of a 16th-century moat are still visible at the Parkin Archeological State Park in eastern Arkansas . The Maya people also used moats, for example in the city of Becan . European colonists in the Americas often built dry ditches surrounding forts built to protect important landmarks, harbours or cities (e.g. Fort Jay on Governors Island in New York Harbor ). Dry moats were

833-405: The siege . Taking considerable time to construct, siege towers were mainly built if the defense of the opposing fortification could not be overcome by ladder assault ("escalade"), by mining , or by breaking walls or gates with tools such as battering rams . The siege tower sometimes housed spearmen , pikemen , and swordsmen or archers and crossbowmen , who shot arrows and quarrels at

882-504: The 8th century BC, siege towers were built by Kush for the army led by Piye (founder of the Nubian 25th dynasty ), in order to enhance the efficiency of Kushite archers and slingers . After leaving Thebes, Piye's first objective was besieging Ashmunein . Having assembled his army for their lack of success so far, the King then undertook the personal supervision of operations including

931-541: The Great Wall of China, and consumed a hundred times more material than the Great Pyramid of Cheops. They took an estimated 150 million hours of digging to construct, and are perhaps the largest single archaeological phenomenon on the planet. Japanese castles often have very elaborate moats, with up to three moats laid out in concentric circles around the castle and a host of different patterns engineered around

980-517: The Nuuanu-Wailau debris avalanches and the Hana slump, overfilled the moat and created a series of sub-basins. These large deposits block the lateral transport of sediment along the Trough, especially in the deepest sections. Storm surges and internal waves trigger mass wasting events from older volcanos on the western side of the ridge, earthquakes provoke this behavior from younger volcanos on

1029-504: The Romans during the siege of Masada (72–73 AD) have survived and can still be seen today. On the other hand, almost all the largest cities were on large rivers, or the coast, and so did have part of their circuit wall vulnerable to these towers. Furthermore, the tower for such a target might be prefabricated elsewhere and brought dismantled to the target city by water. In some rare circumstances, such towers were mounted on ships to assault

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1078-592: The armies of the Neo-Assyrian Empire in the 9th century BC, under Ashurnasirpal II (r. 884 BC – 859 BC). Reliefs from his reign, and subsequent reigns, depict siege towers in use with a number of other siege works, including ramps and battering rams . Centuries after they were employed in Assyria, the use of the siege tower spread throughout the Mediterranean . During the siege of Memphis in

1127-740: The coastal wall of a city: at the Roman siege of Cyzicus during the Third Mithridatic War , for example, towers were used in conjunction with more conventional siege weapons. One of the oldest references to the mobile siege tower in Ancient China was a written dialogue primarily discussing naval warfare . In the Chinese Yuejueshu (Lost Records of the State of Yue ) written by the later Han dynasty author Yuan Kang in

1176-870: The collapse of the Western Roman Empire into independent states, and the Eastern Roman Empire on the defensive, the use of siege towers reached its height during the medieval period. Siege towers were used when the Avars laid siege unsuccessfully to Constantinople in 626, as the Chronicon Paschale recounts: And in the section from the Polyandrion Gate as far as the Gate of St Romanus he prepared to station twelve lofty siege towers, which were advanced almost as far as

1225-550: The deck when not in use, lowering the center of gravity. The biggest siege towers of antiquity, such as the Hellenistic Greek Helepolis (meaning " The Taker of Cities " in Greek ) of the siege of Rhodes in 305 BC by Demetrius I of Macedon , could be as high as 40 m (130 ft) and as wide as 20 m (66 ft). Such large engines would require a rack and pinion to be moved effectively. It

1274-554: The defences – very difficult as well. Segmented moats have one dry section and one section filled with water. Dry moats that cut across the narrow part of a spur or peninsula are called neck ditches . Moats separating different elements of a castle, such as the inner and outer wards, are cross ditches . The word was adapted in Middle English from the Old French motte ( lit.   ' mound, hillock ' ) and

1323-459: The defenders. Because of the size of the tower it would often be the first target of large stone catapults, but it had its own projectiles with which to retaliate. Siege towers were used to get troops over an enemy curtain wall. When a siege tower was near a wall, it would drop a gangplank between it and the wall. Troops could then rush onto the walls and into the castle or city. Some siege towers also had battering rams which they used to bash down

1372-410: The defensive system as an obstacle immediately outside the walls . In suitable locations, they might be filled with water. A moat made access to the walls difficult for siege weapons such as siege towers and battering rams , which needed to be brought up against a wall to be effective. A water-filled moat made the practice of mining – digging tunnels under the castles in order to effect a collapse of

1421-629: The defensive walls around a city or a castle gate. In the First Intermediate Period tomb of General Intef at Thebes (modern Luxor, Egypt ), a mobile siege tower is shown in the battle scenes. In modern Harpoot , Turkey, an artistically Akkadian style stone carved relief dated circa 2000 BC was found depicting a siege tower, the earliest known visual depiction from Anatolia (although siege towers were later described in Hittite cuneiform writing). Siege towers were used by

1470-605: The eastern side. The coral reefs in the Hawaiian Trough are described as mesophotic coral ecosystems , which can be found between 100 and 500 feet below sea level. 43 percent of fish species documented at the mesophotic reefs are unique to the Hawaiian Islands. At Maui's ‘Au’au channel the largest uninterrupted mesophotic coral ecosystem was discovered, with an area larger than 3 square miles. These reefs contained many stony, reef building coral that belong to

1519-485: The erection of a siege tower from which Kushite archers could fire down into the city. During the siege of Syracuse in 413 BC, Athenians erected a siege tower on ship hull. Alexander did the same at Tyre (322 BC) as did Marcellus in Syracuse (214 BC). Towers were used against both land and naval targets. At the time of Emperor Aggripa, ship towers were built with a lighter, collapsible design that could be stowed flat on

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1568-411: The feudal period more commonly had 'dry moats' karabori ( 空堀 , lit.   ' empty moat ' ) , a trench . A tatebori ( 竪堀 , lit.   ' vertical moat ' ) is a dry moat dug into a slope. A unejo tatebori ( 畝状竪堀 , lit.   ' furrowed shape empty moat ' ) is a series of parallel trenches running up the sides of the excavated mountain, and the earthen wall, which

1617-704: The first moat built in England for more than a century. Modern moats may also be used for aesthetic or ergonomic purposes. The Catawba Nuclear Station has a concrete moat around the sides of the plant not bordering a lake. The moat is a part of precautions added to such sites after the September 11, 2001 attacks . Moats, rather than fences, separate animals from spectators in many modern zoo installations. Moats were first used in this way by Carl Hagenbeck at his Tierpark in Hamburg , Germany. The structure, with

1666-459: The genus Leptoseris, which are adapted for deep water environments. These coral environments are not greatly understood because the great depth where they exist make exploration difficult. Moat Some of the earliest evidence of moats has been uncovered around ancient Egyptian fortresses. One example is at Buhen , a settlement excavated in Nubia . Other evidence of ancient moats is found in

1715-399: The important point that the larger siege towers needed level ground. Many castles and hill-top towns and forts were virtually invulnerable to siege tower attack simply due to topography. Smaller siege towers might be used on top of siege-mounds, made of earth, rubble and timber mounds in order to overtop a defensive wall. For example, the remains of such a siege-ramp at Masada , Israel built by

1764-492: The introduction of siege artillery , a new style of fortification emerged in the 16th century using low walls and projecting strong points called bastions , which was known as the trace italienne . The walls were further protected from infantry attack by wet or dry moats, sometimes in elaborate systems. When this style of fortification was superseded by lines of polygonal forts in the mid-19th century, moats continued to be used for close protection. The Walls of Benin were

1813-592: The landscape. The outer moat of a Japanese castle typically protects other support buildings in addition to the castle. As many Japanese castles have historically been a very central part of their cities, the moats have provided a vital waterway to the city. Even in modern times the moat system of the Tokyo Imperial Palace consists of a very active body of water, hosting everything from rental boats and fishing ponds to restaurants. Most modern Japanese castles have moats filled with water, but castles in

1862-541: The last of Hong Gyeong-Rae’s Rebellion made their stand but were beaten back several times by the rebels. In modern warfare, some vehicles used by police tactical units , counterterrorists , and special forces can be fitted with mechanical assault ladders with ramps. These are essentially modernized siege towers with elements of escalade ladders, and are used to raid a structure through its upper levels. These assault ladders are not as large or as tall as their predecessors, and are typically only capable of reaching roughly

1911-552: The locals for building purposes. The walls continue to be torn down for real-estate developments. The Walls of Benin City were the world's largest man-made structure. Fred Pearce wrote in New Scientist: They extend for some 16,000 kilometres in all, in a mosaic of more than 500 interconnected settlement boundaries. They cover 6,500 square kilometres and were all dug by the Edo people. In all, they are four times longer than

1960-413: The outworks, and he covered them with hides. At this siege, the attackers also made use mobile armoured shelters known as sows or cats, which were used throughout the medieval period and allowed workers to fill in moats with protection from the defenders (thus levelling the ground for the siege towers to be moved to the walls). However, the construction of a sloping talus at the base of a castle wall (as

2009-460: The ruins of Babylon, and in reliefs from ancient Egypt, Assyria , and other cultures in the region. Evidence of early moats around settlements has been discovered in many archaeological sites throughout Southeast Asia, including Noen U-Loke, Ban Non Khrua Chut, Ban Makham Thae and Ban Non Wat. The use of the moats could have been either for defensive or agriculture purposes. Moats were excavated around castles and other fortifications as part of

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2058-489: The spiders to jump across. Some specimens were rewarded for jumping then swimming and others for swimming only. Portia fimbriata from Queensland generally succeeded, for whichever method they were rewarded. When specimens from two different populations of Portia labiata were set the same task, members of one population determined which method earned them a reward, whilst members of the other continued to use whichever method they tried first and did not try to adapt. As

2107-534: The year 52 AD, Wu Zixu (526 BC – 484 BC) purportedly discussed different ship types with King Helü of Wu (r. 514 BC – 496 BC) while explaining military preparedness. Before labeling the types of warships used, Wu said: Nowadays in training naval forces we use the tactics of land forces for the best effect. Thus great wing ships correspond to the army's heavy chariots, little wing ships to light chariots, stomach strikers to battering rams , castle ships to mobile assault towers, and bridge ships to light cavalry. With

2156-517: Was Fort Lytton in Brisbane . As Brisbane was much more vulnerable to attack than either Sydney or Melbourne a series of coastal defences was built throughout Moreton Bay , Fort Lytton being the largest. Built between 1880 and 1881 in response to fear of a Russian invasion, it is a pentagonal fortress concealed behind grassy embankments and surrounded by a water-filled moat. Moats were developed independently by North American indigenous people of

2205-1213: Was also called doi ( 土居 , lit.   ' earth mount ' ) , was an outer wall made of earth dug out from a moat. Even today it is common for mountain Japanese castles to have dry moats. A mizubori ( 水堀 , lit.   ' water moat ' ) is a moat filled with water. Moats were also used in the Forbidden City and Xi'an in China; in Vellore Fort in India; Hsinchu in Taiwan ; and in Southeast Asia, such as at Angkor Wat in Cambodia ; Mandalay in Myanmar ; Chiang Mai in Thailand and Huế in Vietnam . The only moated fort ever built in Australia

2254-434: Was common in crusader fortification ) could have reduced the effectiveness of this tactic to an extent. Siege towers also became more elaborate during the medieval period; at the siege of Kenilworth in 1266, for example, 200 archers and 11 catapults operated from a single tower. Even then, the siege lasted almost a year, making it the longest siege in all of English history . They were not invulnerable either, as during

2303-422: Was first applied to the central mound on which a castle was erected (see Motte and bailey ) and then came to be applied to the excavated ring, a 'dry moat'. The shared derivation implies that the two features were closely related and possibly constructed at the same time. The term moat is also applied to natural formations reminiscent of the artificial structure and to similar modern architectural features. With

2352-419: Was manned by 200 soldiers and was divided into nine stories; the different levels housed various types of catapults and ballistae . Subsequent siege towers down through the centuries often had similar engines. However, large siege towers could be defeated by the defenders by flooding the ground in front of the wall, creating a moat that caused the tower to get bogged in the mud. The siege of Rhodes illustrates

2401-542: Was over 16,000 km (9,900 mi) of earth boundaries. It was estimated that earliest construction began in 800 and continued into the mid-15th century. The walls are built of a ditch and dike structure, the ditch dug to form an inner moat with the excavated earth used to form the exterior rampart. The Benin Walls were ravaged by the British in 1897. Scattered pieces of the walls remain in Edo, with material being used by

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