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: ''This article describes the geology of the ceremonial county of Durham. It includes the boroughs of Darlington, Hartlepool and Stockton-on-Tees but not those former northeastern parts of the county which are now in the county of Tyne and Wear.'' The geology of County Durham in northeast England consists of a basement of Lower Palaeozoic rocks overlain by a varying thickness of Carboniferous and Permo-Triassic sedimentary rocks which dip generally eastwards towards the North Sea. These have been intruded by a pluton, sills and dykes at various times from the Devonian Period to the Palaeogene. The whole is overlain by a suite of unconsolidated deposits of Quaternary age arising from glaciation and from other processes operating during the post-glacial period to the present.〔British Geological Survey 1:625,000 scale geological map ''Bedrock Geology UK North'' 5th Edn. NERC 2007〕 The geological interest of the west of the county was recognised by the designation in 2003 of the North Pennines Area of Outstanding Natural Beauty as a European Geopark. The word 'geology' may be traced back to a coinage of Richard de Bury who was a Bishop of Durham in the 14th century. He introduced the term ''geologia'' in his work ''The Philobiblon'' which he explained as 'the earthly science'.〔Lawrence, D.J.D. et al 2004 ''Durham Geodiversity Audit''. Durham: Durham County Council, p8〕 ==Ordovician== The oldest rocks at or near the surface within County Durham are Ordovician age (485 - 443 Ma) Skiddaw Group rocks found in a small inlier near Cronkley Fell in upper Teesdale. They are recorded as the Skiddaw Slates, better known from the Lake District 50 km to the west. A small quarry in these phyllites was worked at one time to make slate pencils.〔DGA p23〕 Overlying these are pyroclastic rocks thought to belong to the Borrowdale Volcanic Group.〔Stone et al 2010 ''British Regional Geology: Northern England'' (5th edition) (Keyworth, Nottingham: British Geological Survey) p18〕 No rocks from the succeeding Silurian Period (443 - 419 Ma) are seen at outcrop in the county. 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「Geology of County Durham」の詳細全文を読む スポンサード リンク
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