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Eramosa Member
The Eramosa Member is a Silurian stratigraphic unit of the Lockport Formation 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, 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. 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Member (stratigraphy)
A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it. Units must be ''mappable'' and ''distinct'' from one another, but the contact need not be particularly distinct. For instance, a unit may be defined by terms such as "when the sandstone component exceeds 75%". Lithostratigraphic units Sequences of sedimentary and volcanic rocks are subdivided on the basis of their shared or associated lithology. Formally identified lithostratigraphic units are structured in a hierarchy of lithostratigraphic rank, higher rank units generally comprising two or more units of lower rank. Going from smaller to larger in rank, the main lithostratigraphic ranks are bed, member, formation, group and supergroup. Formal names of lithostratigraphic units are assigned by geological surveys. Units of formation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
