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The slate industry in Wales began during the Roman period when slate was used to roof the fort at Segontium, now Caernarfon. The slate industry grew slowly until the early 18th century, then expanded rapidly until the late 19th century, at which time the most important slate producing areas were in northwest Wales, including the Penrhyn Quarry near Bethesda, the Dinorwic Quarry near Llanberis, the Nantlle Valley quarries, and Blaenau Ffestiniog, where the slate was mined rather than quarried. Penrhyn and Dinorwig were the two largest slate quarries in the world, and the Oakeley mine at Blaenau Ffestiniog was the largest slate mine in the world.〔Jones p. 72〕 Slate is mainly used for roofing, but is also produced as thicker slab for a variety of uses including flooring, worktops and headstones.〔Lindsay p. 133〕 Up to the end of the 18th century, slate was extracted on a small scale by groups of quarrymen who paid a royalty to the landlord, carted slate to the ports, and then shipped it to England, Ireland and sometimes France. Towards the close of the century, the landowners began to operate the quarries themselves, on a larger scale. After the government abolished slate duty in 1831, rapid expansion was propelled by the building of narrow gauge railways to transport the slates to the ports. The slate industry dominated the economy of north-west Wales during the second half of the 19th century, but was on a much smaller scale elsewhere. In 1898, a work force of 17,000 men produced half a million tons of slate. A bitter industrial dispute at the Penrhyn Quarry between 1900 and 1903 marked the beginning of its decline, and the First World War saw a great reduction in the number of men employed in the industry. The Great Depression and Second World War led to the closure of many smaller quarries, and competition from other roofing materials, particularly tiles, resulted in the closure of most of the larger quarries in the 1960s and 1970s. Slate production continues on a much reduced scale. == Beginnings == The slate deposits of Wales belong to three geological series: Cambrian, Ordovician and Silurian. The Cambrian deposits run south-west from Conwy to near Criccieth; these deposits were quarried in the Penrhyn and Dinorwig quarries and in the Nantlle Valley. There are smaller outcrops elsewhere, for example on Anglesey. The Ordovician deposits run south-west from Betws-y-Coed to Porthmadog; these were the deposits mined at Blaenau Ffestiniog. There is another band of Ordovician slate further south, running from Llangynnog to Aberdyfi, quarried mainly in the Corris area, with a few outcrops in south-west Wales, notably Pembrokeshire. The Silurian deposits are mainly further east in the Dee valley and around Machynlleth.〔Richards 1995 pp. 10–11〕 The virtues of slate as a building and roofing material have been recognized since the Roman period. The Roman fort at Segontium, Caernarfon, was originally roofed with tiles, but the later levels contain numerous slates, used for both roofing and flooring. The nearest deposits are about five miles (8 km) away in the Cilgwyn area, indicating that the slates were not used merely because they were available on-site.〔Lindsay p. 18. Slate flagstones were also used at the smaller fort of Caer Llugwy between Capel Curig and the Conwy Valley.〕 During the mediaeval period, there was small-scale quarrying of slate in several areas. The Cilgwyn quarry in the Nantlle Valley dates from the 12th century, and is thought to be the oldest in Wales.〔Lindsay p. 314〕 The first record of slate quarrying in the neighbourhood of the later Penrhyn Quarry was in 1413, when a rent-roll of Gwilym ap Griffith records that several of his tenants were paid 10 pence each for working 5,000 slates.〔Lindsay p. 27〕 Aberllefenni Slate Quarry may have started operating as a slate mine as early as the 14th century. The earliest confirmed date of operating dates from the early 16th century when the local house Plas Aberllefenni was roofed in slates from this quarry.〔Richards 1995 p. 13〕 Transport problems meant that the slate was usually used fairly close to the quarries. There was some transport by sea. A poem by the 15th century poet Guto'r Glyn asks the Dean of Bangor to send him a shipload of slates from Aberogwen, near Bangor, to Rhuddlan to roof a house at Henllan, near Denbigh.〔Lindsay p. 14〕 The wreck of a wooden ship carrying finished slates was discovered in the Menai Strait and is thought to date from the 16th century. By the second half of the 16th century, there was a small export trade of slates to Ireland from ports such as Beaumaris and Caernarfon.〔Lindsay p. 24〕 Slate exports from the Penrhyn estate are recorded from 1713 when 14 shipments totalling 415,000 slates were sent to Dublin. The slates were carried to the ports by pack-horses, and later by carts. This was sometimes done by women, the only female involvement in what was otherwise an exclusively male industry.〔For example the pack-horses carrying Penrhyn slate were usually tended by girls; see Richards 1999 p. 19〕 Until the late 18th century, slate was extracted from many small pits by small partnerships of local men, who did not own the capital to expand further. The quarrymen usually had to pay a rent or royalty to the landlord, though the quarrymen at Cilgwyn did not. A letter from the agent of the Penrhyn estate, John Paynter, in 1738 complains that competition from Cilgwyn was affecting the sales of Penrhyn slates. The Cilgwyn slates could be extracted more cheaply and sold at a higher price.〔Lindsay pp. 29–30〕 Penrhyn introduced larger sizes of slate between 1730 and 1740, and gave these sizes the names which became standard. These ranged from "Duchesses", the largest at by , through "Countesses", "Ladies" and "Doubles" to the smallest "Singles".〔Lindsay pp, 36–7〕 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「Slate industry in Wales」の詳細全文を読む スポンサード リンク
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