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The Bayfield group is a quartz sandstone found in Wisconsin along the Lake Superior coast.〔Bulletin 1912, p. 25〕 It is named for the village of Bayfield, Wisconsin,〔Eckert, p. 31〕 but was once known as Western Lake Superior Sandstone.〔 Prior to the 1900s, Bayfield group sandstone was also variously named Lake Superior Sandstone, brownstone, or redstone,〔Eckert, p. 33〕 and prefixed by the quarry location. The name was changed to the Bayfield group as its relation to Jacobsville Sandstone (once known as Lake Superior Sandstone) is uncertain.〔 ==Formation== The Bayfield group is irregularly bedded, in contrast to the even, calcareous sandstones in southern Wisconsin.〔Bulletin 1912, p. 29〕 The geological formation is entirely devoid of fossils.〔Bulletin 1912, p. 32〕 The Bayfield group overlies the much thicker Oronto Group.〔Bulletin 1912, p. 48〕 The formation, 4300 feet thick, is divided into three: ''Chequamegon Sandstone'', ''Devils Island Sandstone'', and ''Orienta Sandstone''. The ''Chequamegon Sandstone'' is a red and white sandstone 1000 feet thick. The ''Devils Island Sandstone'' is a 300-foot thick, pink-to-white pure quartz sandtone with significant ripples. The ''Orienta Sandstone'' is 3000 feet thick and similar to the ''Chequamegon Sandstone'', but with a higher feldspar concentration.〔 The Bayfield group is a member of the Keweenawan Supergroup. 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「Bayfield group」の詳細全文を読む スポンサード リンク
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