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Clearwell Caves, at Clearwell in the Forest of Dean, Gloucestershire, England, is a natural cave system which has been extensively mined for iron ore. It now operates primarily as a mining museum. The caves are part of a Natural England designated Site of Special Scientific Interest and the notification includes parts of Clearwell along with Old Bow, Lambsquay and Old Ham mine complexes.〔( Natural England SSSI information on the citation, map and units of assessment )〕 ==Mining== The caves were formed by underground streams around 330 million years ago.〔(Clearwell Caves, Geology )〕 They have been mined for iron ore possibly as far back as Roman times〔(Clearwell Caves )〕 and extensively in the last century, which considerably enlarged and extended the network of natural caverns. Ochre has been mined here for even longer.〔(Clearwell Caves, Ochre )〕 The nearby scowles at the (Forest )] and Puzzlewood represent similar shallow mines which have been exposed from above. The mine is still worked intermittently to produce coloured ochres for use as natural pigments. These are milled and sold in the mine's own shop. A range of ochre colours are available, from golden yellow to English Reds. Clearwell is also known as one of the few locations where the rare purple ochre may be found. Nine chambers are easily accessible from ground level, and represent the earliest and most complete workings of the mine. A network of much deeper chambers does exist, but can only be visited in the presence of a guide and with appropriate caving clothing for safety. The upper caves are open to the public without special equipment. 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「Clearwell Caves」の詳細全文を読む スポンサード リンク
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