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''For other locations of the same name, see The Undercliff''. The Undercliff, Isle of Wight, England is a tract of semi-rural land, around 5 miles long by 0.25–0.5 miles wide, skirting the southern coast of the island from Niton to Bonchurch. Named after its position below the escarpment that backs this coastal section, its undulating terrain comprises a mix of rough pasture, secondary woodland, parkland, grounds of large isolated houses, and suburban development. Its sheltered south-facing location gives rise to a microclimate considerably warmer than elsewhere on the island.〔(Introduction ), Ventnor Botanic Garden website (retrieved 9 July 2013)〕 Although inhabited, the Undercliff is an area prone to landslips and subsidence, with accompanying loss of property over time. Settlements along the Undercliff, from west to east, are: lower Niton (also called Niton Undercliff), Puckaster, St Lawrence, Steephill, the town of Ventnor, and Bonchurch. == Geology == The Undercliff is a landslide complex in Cretaceous soft rocks, a bench of slipped clays and sands above a low sea-cliff, backed by higher (100 metres) Upper Greensand and Chalk cliffs.〔(Luccombe-Blackgang Isle of Wight (United Kingdom) ), Robin G. McGiness, (Isle of Wight Centre for Coastal Environment )〕 The largest urban landslide complex in northern Europe, it dates from two main phases of landslides after the last Ice age: 8000–4500 years and 2500–1800 years ago.〔(ed) Hungr, O., Fell, R., Couture, R., Eberhardt, E. ''Landslide Risk Management'', Taylor & Francis, 2010, p183〕 It is flanked by highly active landslip zones that have seen major slides over the past two centuries: the Blackgang landslip at the west, and the Bonchurch Landslips at the east. The main section is more stable, though there are ongoing concerns over coastal erosion, further slippage and subsidence.〔〔 (West & South Isle of Wight ), Standing Conference on Problems Associated with the Coastline.〕 The main through road, Undercliff Drive, was disrupted by a mud slide near St Lawrence in 2001, requiring 18 months to build a new road section〔Watching coastline crumble, ''Daily Echo'', Southampton, 31 October 2002〕 and in 2014 further erosion after heavy rain fell and the road was under repair, leading to more damage, and nine houses being evacuated.〔(BBC News Online )〕 Interactions between the heavy chalk-based rocks of St. Boniface Down, the highest chalk downland on the Isle of Wight, and the softer rocks of the Undercliff below Ventnor means that subsequent erosion has caused Upper Ventnor, or Lowtherville, to gradually start moving towards the cliff edge, in a feature referred to residents as 'The Graben'. 〔http://blogs.agu.org/landslideblog/2014/12/19/ventnor-paper-1/〕 This rapid geological change in terrain is also responsible for necessitating the town's distinctive routes in and out of Ventnor, which feature panoramic views across Sandown Bay to the north-east, and the English Channel to the south. Ventnor's microclimate is also created by the shelter of St. Boniface Down. 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「Undercliff (Isle of Wight)」の詳細全文を読む スポンサード リンク
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