|
The Doom Bar (previously known as Dunbar sands, Dune-bar, and similar names) is a sandbar at the mouth of the estuary of the River Camel, where it meets the Celtic Sea on the north coast of Cornwall, England. Like two other permanent sandbanks further up the estuary, the Doom Bar is composed mainly of marine sand that is continually being carried up from the seabed. More than 60 percent of the sand is derived from marine shells, making it an important source of agricultural lime, which has been collected for hundreds of years; an estimated 10 million tons of sand or more has been removed from the estuary since the early nineteenth century, mainly by dredging. The estuary mouth, exposed to the Atlantic Ocean, is a highly dynamic environment, and the sands have been prone to dramatic shifts during storms. According to tradition, the Doom Bar formed in the reign of Henry VIII, damaging the prosperity of the port of Padstow a mile up the estuary. Until the twentieth century, access to Padstow's harbour was via a narrow channel between the Doom Bar and the cliffs at Stepper Point, a difficult passage for sailing ships to navigate especially in north-westerly gales when the cliffs would cut off the wind. Many ships were wrecked on the Doom Bar, despite the installation of mooring rings and capstans on the cliffs and quarrying away part of Stepper Point to improve the wind. In the early twentieth century the main channel moved away from the cliffs, and continued dredging has made it much safer for boats, but deaths have occurred on the bar as recently as 1997. A Cornish folklore legend relates that a mermaid created the bar as a dying curse on the harbour after she was shot by a local man. The Doom Bar has been used in poetry to symbolise feelings of melancholy, and it has given its name to the flagship ale from Sharp's Brewery. == Description == The Doom Bar is a sandbar at the mouth of the Camel estuary on the north coast of Cornwall. The bar is composed mostly of coarse sediment carried up from the seabed by bed load processes, and it has been shown that there is a net inflow of sediment into the estuary.〔Cornwall SMP2, pp. 41–42.〕 This inflow is aided by wave and tidal processes, but the exact patterns of sediment transport within the estuary are complex and are not fully understood.〔 There is only a very small sediment contribution from the River Camel itself: most of the river's sediment is deposited much higher up the estuary.〔Cornwall SMP2, p. 40.〕 There are three persistent sandbars in the Camel estuary: the Doom Bar; the Town Bar at Padstow, about upstream; and the Halwyn Bank just upstream of Padstow, where the estuary changes direction.〔Cornwall SMP2, p. 35.〕 All three are of similar composition; a large proportion of their sediment is derived from marine mollusc shells,〔Cornwall SMP2, p. 39.〕 and as a consequence it includes a high level of calcium carbonate, measured in 1982 at 62 per cent.〔 The high calcium carbonate content of the sand has meant that it has been used for hundreds of years to improve agricultural soil by liming. This use is known to date back to before 1600.〔 High calcium carbonate levels combined with natural sea salt made the sand valuable to farmers as an alkaline fertiliser when mixed with manure.〔 In a report published in 1839, Henry De la Beche estimated that the sand from the Doom Bar accounted for between a fifth and a quarter of the sand used for agriculture in Devon and Cornwall.〔 He also stated that around 80 men were permanently employed to dredge the area from several barges, removing an estimated of sand per year, which he said he had been "assured by competent persons" had caused a reduction in height of the bar of between in the 50 years before 1836.〔 Another report, published about twenty years earlier by Samuel Drew, stated, however, that although the sandbars had been "pillaged" for ages they remained undiminished.〔 An estimated ten million tons of sediment was removed from the estuary between 1836 and 1989, mostly for agricultural purposes and mostly from the Doom Bar.〔 Sand is still regularly dredged from the area; in 2009 an estimated 120,000 tons of sand were removed from the bar and the surrounding estuary.〔 There is a submerged forest beneath the eastern part of the Doom Bar, off Daymer Bay.〔 It is believed to be part of the wooded plain that existed off the current Cornwall coast before it was overcome by sand dunes and beach sand during the last significant rise in sea-level, which ended around 4,000 years ago.〔 Exposed as they are to the Atlantic Ocean, the sands of the area have always been prone to sudden shifts: several houses were said to have been buried one night during a powerful storm.〔 According to tradition one such shift led to the formation of the Doom Bar during the reign of Henry VIII (1509–1547), causing a decline in the prosperity of Padstow.〔 Today, the sandbank covers approximately , linking the beaches near Harbour Cove by sand flats, although the actual size and shape varies.〔Cornwall SMP2, p. 43.〕 The name "Doom Bar" is a corruption of the older name ''Dunbar'' which itself derives from ''dune-bar''.〔〔 Although the bar was commonly known as "Dunbar sands" before 1900, the name "Doom Bar" was used in 1761 (as "the Doom-bar"),〔 and it was also used in poetry,〔 and in House of Commons papers in the nineteenth century.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Doom Bar」の詳細全文を読む スポンサード リンク
|