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Ramsey Island (Welsh: ''Ynys Dewi'') is an island about 1 km off the coast of the St David's peninsula in Pembrokeshire on the northern side of St Brides Bay, in southwest Wales. It is 640 acres (2.59 square km) in extent. In Welsh the island is named after Saint David (''Dewi Sant''), the patron saint of Wales. It was the home of his confessor, Saint Justinian. The nearest town, strictly a city, is St David's. Ramsey Island is less than 3.2 km (2 mi) long and its highest point is 136 metres (446 ft) above sea level at Carnllundain, and is listed as a HuMP. It is the fourth largest island in Wales, after Anglesey, Holy Island and Skomer.〔The Rough Guide to Wales, Rough Guides, Rough Guide Travel Guides, Mike Parker, Paul Whitfield, 4, illustrated, Rough Guides, 2003, ISBN 1-84353-120-8, ISBN 978-1-84353-120-3, pg. 194〕 ==Geology== The island has a diverse geology for a relatively small area; it comprises sedimentary, volcanic and intrusive igneous rocks dating from the early Palaeozoic Era. The larger part of the north of the island is formed from mudstones of the Tetragraptus Mudstone Formation (also known as the 'Penmaen Dewi Shale Formation' and again as the 'Road Uchaf Formation' (sic) after the Rhod Uchaf locality on the island's east coast). However Carnysgubor stands proud to their west as it is formed from a more resistant microtonalite intrusion. In contrast the coastal cliffs between Trwyn-drain-du and Trwyn-Sion-Owen and also between Trwyn Ogof Hen and Rhod Uchaf are formed by sedimentary rocks, the mica-rich Lingula Flags and the sandstones and mudstones of the Ogof Hen Formation. The rock strata is typically steeply tilted and commonly faulted. Running NW-SE across the centre of the island from Aber Mawr to the vicinity of The Bitches is a band of late Arenig age tuffs and 'pencil slates' assigned to the Abermawr Formation. Its boundary with the sediments to the north is a fault. The south of the island is dominated by a rhyolite intrusion as are the islets off its southern coast. To the west of the Ramsey Fault which runs from Aber Mawr to Porth Lleuog, is Carnllundain which is formed from the tough rhyolitic tuffs of the Carn Llundain Formation. These tuffs arose as volcanic ash falls, ash flows and turbidite deposits. Smaller areas of dark grey mudstones interbedded with debris flows grouped together as the Porth Llauog Formation occur around the margins of the rhyolite. Part of the southern margin of the inlet of Aber Mawr is characterised by the mudstones and sandstones of the Trwyn Llundain Formation, a part of the Solva Group of Cambrian rocks.〔British Geological Survey 1992 1:50,000 scale provisional geological map sheet 209 (England and Wales) ''St David's''〕〔Howells, M.F. 2007 ''British Regional Geology: Wales'' (Keyworth, Nottingham, British Geological Survey) pp45-51〕 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「Ramsey Island」の詳細全文を読む スポンサード リンク
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