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Ridgeways are a particular type of ancient road that exploits the hard surface of hilltop ridges for use as unpaved, zero-maintenance roads, though they often have the disadvantage of steeper gradients along their courses, and sometimes quite narrow widths. Before the advent of turnpikes or toll roads, ridgeway trails continued to provide the firmest and safest cart tracks. They are generally an opposite to level, valley-bottom, paved roads, which require engineering work to shore up and maintain. Unmaintained valley routes may require greater travelling distances than ridgeways. Prehistoric roads in Europe often variously comprised stretches of ridgeway above the line of springs, sections of causeway through bog and marsh, and other trackways of neither sort which crossed flat country. A revival of interest in ancient roads and recreational walking in the 19th century brought the concept back into common use. Some ancient routes, in particular The Ridgeway National Trail of southern England, have been reprised as long-distance footpaths. ==Origin== Along ridge lines of hills, soil is often exposed and dry because of wind and natural drainage, and vegetation tends to be thinner. Where a beaten track evolves into a busier "road," constant passage by beasts, sleds and wheeled vehicles suppresses regrowth of vegetation. With the help of rain (and soil creep), a shallow trail can be worn down into the topsoil and smoothed without any purposeful road-making work. The thin soil and rocky subsoil, combined with the natural drainage provided by the slopes on each side, also tended to keep such roads dry. In western Europe, where prehistoric roads have been extensively documented with the help of itineraries, traces on old maps and extant marks on the landscape, ridgeways are a typical feature of long-distance ancient routes through rugged, high-rainfall parts of Germany and across the island of Great Britain. These ancient trackways generally ran along the hilltops, only descending when necessary to cross valleys.〔Landau〕 As such, they are an opposite to modern-style roads, which tend to run along the valleys and only ascend when necessary to cross the hilltops.〔Weimann, Reinhold.〕 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「Ridgeway (road)」の詳細全文を読む スポンサード リンク
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