Rhuddanian
Rhuddanian | |||||||||||||
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443.8 ± 1.5 – 440.8 ± 1.2 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓ | |||||||||||||
Chronology | |||||||||||||
In the geologic timescale, the Rhuddanian is the first age of the Silurian Period and of the Llandovery Epoch. The Silurian is in the Paleozoic Era of the Phanerozoic Eon.[6] The Rhuddanian Age began 443.8 ± 1.5 Ma and ended 440.8 ± 1.2 Ma (million years ago). It succeeds the Himantian Age (the last age of the Ordovician Period) and precedes the Aeronian Age.[7] GSSPThe GSSP for the Silurian is located in a section at Dob's Linn, Scotland, in an artificial excavation created just north of the Linn Branch Stream. Two lithological units (formations) occur near the boundary.[6] The lower is the Hartfell Shale (48 metres (157 ft) thick), consisting chiefly of pale gray mudstone with subordinate black shales and several interbedded meta-bentonites.[6] Above this is the 43 metres (141 ft) thick Birkhill Shale, which consist predominantly of black graptolitic shale with subordinate gray mudstones and meta-bentonites.[8] The name is given after Cefn-Rhuddan Farm, Llandovery in Carmarthenshire, Wales. See alsoReferences
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Cenozoic Era (present–66.0 Ma) |
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Mesozoic Era (66.0–252 Ma) |
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Paleozoic Era (252–539 Ma) |
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Proterozoic Eon (539 Ma–2.5 Ga) |
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Archean Eon (2.5–4 Ga) | |||||||||||||
Hadean Eon (4–4.6 Ga) | |||||||||||||
ka = kiloannum (thousands years ago); Ma = megaannum (millions years ago); Ga = gigaannum (billions years ago). See also: Geologic time scale • ![]() ![]() |
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