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49-602: The Post Track is an ancient causeway in the valley of the River Brue on the Somerset Levels , England. It dates from around 3838 BCE, making it some 30 years older than the Sweet Track in the same area. Various sections have been scheduled as ancient monuments . The timber trackway was constructed of long ash planks, with lime and hazel posts spaced along three-metre intervals. According to Coles,

98-658: A dyke that keeps two bodies of water apart, such as bodies with a different water level on each side, or with salt water on one side and fresh water on the other. This may also be the primary purpose of a structure, the road providing a hardened crest for the dike, slowing erosion in the event of an overflow. It also provides access for maintenance as well perhaps, as a public service. Notable causeways include those that connect Singapore and Malaysia (the Johor-Singapore Causeway ), Bahrain and Saudi Arabia (25-km long King Fahd Causeway ) and Venice to

147-478: A morass on an artificial foundation of timber filled with brushwood, bracken , rubble, and clay . The remains of similar tracks have been uncovered nearby, connecting settlements on the peat bog ; they include the Honeygore, Abbotts Way, Bells, Bakers, Westhay, and Nidons trackways. Sites such as the nearby Meare Pool provide evidence that the purpose of these structures was to enable easier travel between

196-448: A distance close to 1,800 metres (5,900 ft) or around 1.1 mi. The track is one of a network that once crossed the Somerset Levels . Various artifacts and prehistoric finds, including a jadeitite ceremonial axe head, have been found in the peat bogs along its length. Construction was of crossed wooden poles, driven into the waterlogged soil to support a walkway that consisted mainly of planks of oak , laid end-to-end. The track

245-418: A fuller mapping of the rings, and their relationship with the climate of the period. The wood used to build the track is now classed as bog-wood , the name given to wood (of any source) that for long periods (sometimes hundreds of thousands of years) has been buried in peat bogs, and kept from decaying by the acidic and anaerobic bog conditions. Bog-wood usually is stained brown by tannins dissolved in

294-436: A major color imbalance (as can be seen in the image at right). Furthermore, the difference in salinity has become so severe that native brine shrimp cannot survive in much of the waters, with the northern part being too salty and the southern part being insufficiently salty. Sweet Track The Sweet Track is an ancient trackway , or causeway , in the Somerset Levels , England, named after its finder, Ray Sweet. It

343-553: A much higher bridge (or part of a single bridge) in the middle so that taller boats may pass underneath safely. Causeways are most often used to connect the barrier islands with the mainland . In the case of the Courtney Campbell Causeway , however, the mainland ( Hillsborough County ) is connected by a causeway to a peninsula ( Pinellas County ). A well-known causeway is the NASA Causeway connecting

392-540: A plank from the track to John Coles , an assistant lecturer in archaeology at Cambridge University , who had carried out some excavations on nearby trackways. Coles' interest in the trackways led to the Somerset Levels Project, which ran from 1973 to 1989, funded by various donors including English Heritage . The project undertook a range of local archaeological activities, and established the economic and geographic significance of various trackways from

441-527: A short stretch of viaduct is called an overpass . The distinction between the terms causeway and viaduct becomes blurred when flood-relief culverts are incorporated, though generally a causeway refers to a roadway supported mostly by earth or stone, while a bridge supports a roadway between piers (which may be embedded in embankments). Some low causeways across shore waters become inaccessible when covered at high tide . The Aztec city-state of Tenochtitlan had causeways supporting roads and aqueducts. One of

490-515: A word derived not from trampling but from ramming or tamping. The Welsh word cawsai translates directly to the English word 'causeway'; it is possible that, with Welsh being a lineal linguistic descendant of the original native British tongues, the English word derives from the Welsh. A transport corridor that is carried instead on a series of arches, perhaps approaching a bridge, is a viaduct ;

539-477: Is a high priority for local, regional, and even national authorities. Causeways can separate populations of wildlife, putting further pressure on endangered species . Causeways can cause a mineral imbalance between portions of a body of water. For example, a causeway built in the Great Salt Lake has caused the northern half of the lake to have much higher salinity, to the point that the two halves show

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588-464: Is simply the hard, trodden surface of a path. The name by this route came to be applied to any firmly surfaced road. It is now little-used except in dialect and in the names of roads which were originally notable for their solidly made surface. The 1911 Encyclopædia Britannica states: "causey, a mound or dam, which is derived, through the Norman-French caucie (cf. modern chaussée ), from

637-480: Is used on the one hand for a metalled carriageway, and on the other for an embankment with or without a road. Other languages have a noun with similar dual meaning. In Welsh , it is sarn . The Welsh is relevant here, as it also has a verb sarnu , meaning to trample. The trampling and ramming technique for consolidating earthworks was used in fortifications and there is a comparable, outmoded form of wall construction technique, used in such work and known as pisé,

686-486: The National Heritage Memorial Fund , and installation of a water pumping and distribution system along a 500-metre (1,600 ft) section, several hundred metres of the track's length are now being actively conserved. This method of preserving wetland archaeological remains (maintaining a high water table and saturating the site) is rare. A 500-metre (1,600 ft) section, which lies within

735-720: The Shapwick Heath Nature Reserve involves the Nature Conservancy Council, the Department for Environment, Food and Rural Affairs , and the Somerset Levels Project. Although the wood recovered from the Levels was visually intact, it was extremely degraded and very soft. Where possible, pieces of wood in good condition, or the worked ends of pegs, were taken away and conserved for later analysis. The conservation process involved keeping

784-412: The X shapes to form the walkway. In some places a second rail was placed on top of the first one to bring the plank above it level with the rest of the walkway. Some of the planks were then stabilised with slender, vertical wooden pegs driven through holes cut near the end of the planks and into the peat, and sometimes the clay, beneath. At the southern end of the construction smaller trees were used, and

833-544: The acidic water, and represents an early stage of fossilisation . The age of the track prompted large-scale excavations in 1973, funded by the Department of the Environment . In 1973 a jadeitite axehead was found alongside the track; it is thought to have been placed there as an offering. One of over 100 similar axe heads found in Britain and Ireland, its good condition and its precious material suggest that it

882-832: The area) was donated to the British Museum in London. Although this short section can be assembled for display purposes, it is currently kept in store, off site, and under controlled conditions. A reconstructed section was displayed at the Peat Moors Centre near Glastonbury . The centre was run by the Somerset Historic Environment Service, but was closed in October 2009 as a result of budget cuts imposed by Somerset County Council . The main exhibits are extant, but future public access

931-720: The cobbles together. However, some of the stones were left loose. In Scotland , the skirmish known as Clense the Calsey, or Cleanse the Causeway , took place in the High Street of Edinburgh in 1520. In the 18th century, Dahomey lacked an effective navy hence it built causeways for naval purposes starting in 1774. The modern embankment may be constructed within a cofferdam : two parallel steel sheet pile or concrete retaining walls , anchored to each other with steel cables or rods. This construction may also serve as

980-564: The elements. Some of the wood planks also were reused in the Sweet Track when it was built making the specific dating more complex. Causeway When first used, the word causeway appeared in a form such as "causey way", making clear its derivation from the earlier form "causey". This word seems to have come from the same source by two different routes. It derives ultimately, from the Latin for heel, calx , and most likely comes from

1029-458: The entrance of the Harbour made from blocks of reef and coral nearly a meter high. These acted as breakwaters , allowing mangroves to grow which is one of the ways the breakwater can be spotted from a distance. Some parts of the causeway are made from the bedrock, but usually the bedrock was used as a base. Coral stone was also used to build up the causeways, with sand and lime being used to cement

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1078-522: The harbour, on the orders of Winston Churchill . The Estrada do Istmo connecting the islands of Taipa and Coloane in Macau was initially built as a causeway. The sea on both sides of the causeway then became shallower as a result of silting, and mangroves began to conquer the area. Later, land reclamation took place on both sides of the road and the area has subsequently been named Cotai and become home to several casino complexes. Various causeways in

1127-503: The heavy planks of the Post Track were seldom pegged. The track follows closely in line with the Sweet Track and, before the planks were dated, it was posited that it served as a construction platform for the Sweet Track. It is speculated that it led to places of spiritual significance. It is likely that the route was intended to be a permanent fixture, with the track being updated, maintained, and eventually replaced as it succumbed to

1176-402: The islands in the bog was sufficiently pressing for them to mount the enormous communal activity required for the task of stockpiling the timber and building the trackway, presumably when the waters were at their lowest after a dry period. The work required for the construction of the track demonstrates that they had advanced woodworking skills and suggests some differentiation of occupation among

1225-507: The land owned by the Nature Conservancy Council , has been surrounded by a clay bank to prevent drainage into surrounding lower peat fields, and water levels are regularly monitored. The viability of this method is demonstrated by comparing it with the nearby Abbot's Way, which has not had similar treatment, and which in 1996 was found to have become dewatered and desiccated. Evaluation and maintenance of water levels in

1274-451: The late Latin via calciata , a road stamped firm with the feet ( calcare , to tread)." The word is comparable in both meanings with the French chaussée , from a form of which it reached English by way of Norman French . The French adjective chaussée carries the meaning of having been given a hardened surface and is used to mean either paved or shod. As a noun chaussée

1323-555: The levels were heavily wooded, but local inhabitants began to clear these forests about this time to make way for an economy that was predominately pastoral with small amounts of cultivation. During the winter, the flooded areas of the levels would have provided this fishing, hunting, foraging and farming community with abundant fish and wildfowl; in the summer, the drier areas provided rich, open grassland for grazing cattle and sheep, reeds, wood, and timber for construction, and abundant wild animals, birds, fruit, and seeds. The need to reach

1372-808: The mainland, all of which carry roadways and railways. In the Netherlands there are a number of prominent dikes which also double as causeways, including the Afsluitdijk , Brouwersdam , and Markerwaarddijk . In the Republic of Panama a causeway connects the islands of Perico, Flamenco, and Naos to Panama City on the mainland. It also serves as a breakwater for ships entering the Panama Canal . Causeways are also common in Florida , where low bridges may connect several human-made islands , often with

1421-575: The oldest engineered roads yet discovered is the Sweet Track in England . Built in 3807 or 3806 BC, the track was a walkway consisting mainly of planks of oak laid end-to-end, supported by crossed pegs of ash , oak, and lime , driven into the underlying peat. In East Africa , the Husuni Kubwa (the "Great Fort"), situated outside the town of Kilwa , was an early 14th-century sultan's palace and emporium that contained causeways and platforms at

1470-423: The pegs suggest that they were taken from coppiced woodland. Longitudinal log rails up to 6.1 metres (20 ft) long and 7.6 centimetres (3.0 in) in diameter, made of mostly hazel and alder , were laid down and held in place with the pegs, which were driven at an angle across the rails and into the peat base of the bog. Notches were then cut into the planks to fit the pegs, and the planks were laid along

1519-424: The planks split across the grain to utilise the full diameter of the trunk. Fragments of other tree species including holly , willow , poplar , dogwood , ivy , birch , and apple have also been found. The wetland setting indicates that the track components must have arrived prefabricated , before being assembled on site, although the presence of wood chips and chopped branches indicates that some trimming

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1568-621: The same line as the original, in Shapwick Heath National Nature Reserve . In the early fourth millennium BC the track was built between an island at Westhay and a ridge of high ground at Shapwick close to the River Brue . A group of mounds at Westhay mark the site of prehistoric lake dwellings, which were likely to have been similar to those found in the Iron Age Glastonbury Lake Village near Godney , itself built on

1617-543: The settlements. Investigation of the Meare Pool indicates that it was formed by the encroachment of raised peat bogs around it, particularly during the Subatlantic climatic period (1st millennium BC), and core sampling demonstrates that it is filled with at least 2 metres (6.6 ft) of detritus mud. The two Meare Lake Villages within Meare Pool appear to originate from a collection of structures erected on

1666-425: The surface of the dried peat, such as tents, windbreaks and animal folds. Clay was later spread over the peat, providing raised stands for occupation, industry and movement, and in some areas thicker clay spreads accommodated hearths built of clay or stone. The track was discovered in 1970 during peat excavations and is named after its finder, Ray Sweet. The company for which he worked, E. J. Godwin, sent part of

1715-596: The third and first millennia BC. The work of John Coles, Bryony Coles , and the Somerset Levels Project was recognised in 1996 when they won the Imperial Chemical Industries (ICI) Award for the best archaeological project offering a major contribution to knowledge, and in 2006 with the European Archaeological Heritage Prize. Dendrochronology (tree-ring dating) of the timbers has enabled precise dating of

1764-664: The town of Titusville on the Florida mainland to the rocket-launching facility at the Kennedy Space Center on Merritt Island . The Churchill Barriers in Orkney are some of the most notable sets of causeways in Europe. Constructed in waters up to 18 metres deep, the four barriers link five islands on the eastern side of the natural harbour at Scapa Flow . They were built during World War II as military defences for

1813-548: The track, showing it was built in 3807 BC. This dating led to claims that the Sweet Track was the oldest roadway in the world, until the discovery in 2009 of a 6,000-year-old trackway built in 4100 BC, in Plumstead , near Belmarsh prison . Analysis of the Sweet Track's timbers has aided research into Neolithic Era dendrochronology; comparisons with wood from the River Trent and a submerged forest at Stolford enabled

1862-432: The trampling technique to consolidate earthworks . Originally, the construction of a causeway used earth that had been trodden upon to compact and harden it as much as possible, one layer at a time, often by slaves or flocks of sheep . Today, this work is done by machines. The same technique would have been used for road embankments, raised river banks, sea banks and fortification earthworks. The second derivation route

1911-435: The winds and rains of approaching tropical storms —as well as waves generated by the storm in the surrounding bodies of water—make traversing causeways problematic at best and impossibly dangerous during the fiercest parts of the storms. For this reason (and related reasons, such as the need to minimize traffic jams on both the roads approaching the causeway and the causeway itself), emergency evacuation of island residents

1960-424: The wood in heated tanks in a solution of polyethylene glycol and, by a process of evaporation, gradually replacing the water in the wood with the wax over a period of about nine months. After this treatment the wood was removed from the tank and wiped clean. As the wax cooled and hardened, the artefact became firm and could be handled freely. A section of the track on land owned by Fisons (who extracted peat from

2009-399: The wood may be influencing the peat's hydrology , causing the loss or collection of minerals within the pore water and peat matrix. The community that constructed the trackway were Neolithic farmers who had colonised the area around 3900 BC, and the evidence suggests that they were, by the time of construction, well organised and settled. Before this human incursion, the uplands surrounding

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2058-648: The workers. They also appear to have been managing the surrounding woodland for at least 120 years. Built in 3807 or 3806 BC, the track was a walkway consisting mainly of planks of oak laid end-to-end, supported by crossed pegs of ash , oak, and lime , driven into the underlying peat. The planks, which were up to 40 centimetres (16 in) wide, 3 metres (120 in) long and less than 5 centimetres (2.0 in) thick, were cut from trees up to 400 years old and 1 metre (39 in) in diameter, felled and split using only stone axes, wooden wedges, and mallets. The length, straightness, and lack of forks or branches in

2107-500: The world: Unlike tunnels or bridges, causeways do not permit shipping through the strait which can cause problems. In some cases, causeways were built with "gates" or other facilities to permit shipping to pass through. Causeways affect currents and may therefore be involved in beach erosion or changed deposition patterns; this effect has been a problem at the Hindenburgdamm in northern Germany. During hurricane seasons,

2156-538: Was a symbolic axe, rather than one used to cut wood. Because of the difficulty of working this material, which was derived from the Alpine area of Europe, all the axe heads of this type found in Great Britain are thought to have been non-utilitarian and to have represented some form of currency or be the products of gift exchange. Radiocarbon dating of the peat in which the axe head was discovered suggests that it

2205-609: Was built in 3807 BC (determined using dendrochronology - Tree-ring dating) and is the second-oldest timber trackway discovered in the British Isles, dating to the Neolithic . The Sweet Track was predominantly built along the course of an earlier structure, the Post Track . The track extended across the now largely drained marsh between what was then an island at Westhay and a ridge of high ground at Shapwick ,

2254-444: Was deposited in about 3200 BC. Wooden artefacts found at the site include paddles, a dish, arrow shafts, parts of four hazel bows, a throwing axe , yew pins, digging sticks, a mattock , a comb, toggles, and a spoon fragment. Finds made from other materials, such as flint flakes, arrowheads, and a chipped flint axe (in mint condition) have also been made. A geophysical survey of the area in 2008 showed unclear magnetometer data;

2303-534: Was in daily use as part of the farming life of the community. Since its discovery, it has been determined that parts of the Sweet Track were built along the route of an even earlier track, the Post Track , which was constructed thirty years earlier in 3838 BC. Most of the track remains in its original location, which is now within the Shapwick Heath biological Site of Special Scientific Interest and National Nature Reserve . Following purchase of land by

2352-421: Was performed locally. The track was constructed from about 200,000 kilograms (440,000 lb) of timber, but Coles estimates that once the materials were transported to the site, ten men could have assembled it in one day. The Sweet Track was used only for about ten years; rising water levels may have engulfed it, and therefore curtailed its use. The variety of objects found alongside the track suggest that it

2401-600: Was used for a period of only around ten years and was then abandoned, probably due to rising water levels. Following its discovery in 1970, most of the track has been left in its original location, with active conservation measures taken, including a water pumping and distribution system to maintain the wood in its damp condition. Some of the track is stored at the British Museum and at the Museum of Somerset in Taunton. A reconstruction has been made on which visitors can walk, on

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