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Eramosa
The Eramosa is a Silurian stratigraphic unit exposed along the Niagara Escarpment in Ontario and western New York State. In the late nineteenth century it was an important source of building stone in Hamilton, Ancaster and Waterdown,〔http://www.raisethehammer.org/article/1441/hamilton_building_stone_part_2:_eramosa_dolomite Middleton, G.V., 2011 "Hamilton Building Stone, Part 2: Eramosa Dolomite."〕 and in the late twentieth century quarries in a similar unit, also called the Eramosa, near Wiarton in the Bruce Peninsula, became an important source of dimension stone at a time when most of the other resources of similar stone were depleted. Work in these quarries led to the discovery of exceptionally well preserved fossils (the Eramosa lagerstätte). On the east Mountain at Hamilton, a well-developed cave system was discovered in the Eramosa and has now been designated as the Eramosa Karst Conservation Area.〔http://www.conservationhamilton.ca/area-information/conservation-areas/area-information/eramosa-karst〕
==Stratigraphy==
The term was first used for a stratigraphic unit by Williams (1915) who named the Eramosa Member (of the Lockport Formation) for the bituminous dolomites exposed below the Guelph Formation along the Eramosa River, northeast of Guelph, Ontario. No detailed description of the type section has ever been published, and the status of the unit has been subject to many different interpretations. Until recently, the Eramosa in Ontario was regarded as the highest Member of the Lockport Formation,〔''Geology of Ontario'', v.2, p. 955, 1992〕 with gradational contacts with the Goat Island Member (below) and the Guelph Formation (above). In 1995, the US Geological Survey 〔''U.S.G.S. Bulletin'' 2086〕 proposed a revised stratigraphy based on studies in the Niagara region. It extended the Lockport to Group status and included, from base to top, the Gasport, Goat Island, Eramosa, and Guelph as Formations within the Lockport Group. In a “reference section” in the Niagara River Gorge, the Eramosa was divided into six “units” recognized throughout the Niagara region, but a shaley lower unit previously named for the Hamilton area (the Vinemount Member) was transferred to the Goat Island Formation. Brunton (2009) has proposed a revision for Ontario which restores the Vinemount Member to the Eramosa and recognizes two other members.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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