Drumian
Key events in the Cambrian
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Stratigraphic scale of the ICS subdivisions and Precambrian/Cambrian boundary.
Coordinates: 39°30′42″N 112°59′29″W / 39.5117°N 112.9915°W / 39.5117; -112.9915
The Drumian is a stage of 3rd series of the Cambrian. It succeeds still unnamed 5th stage of the Cambrian and precedes the Guzhangian. The base is defined as the first appearance of the trilobite Ptychagnostus atavus around ~504.5 million years ago. The top is defined as the first appearance of another trilobite Lejopyge laevigata around ~500.5 million years ago.
The GSSP is defined in the Drumian section (39°30′42″N 112°59′29″W / 39.5117°N 112.9915°W / 39.5117; -112.9915) in the Drum Mountains, Millard County, Utah, USA.[1] The stage was also named after the Drum mountains. The section is an outcrop of the Wheeler Formation, a succession of calcareous shales. The precise base of the Drumian is a laminated limestone 62 m above the base of the Wheeler Formation.[2]
References
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| | Early (485.4–470.0 Mya) | |
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| Middle (470.0–458.4 Mya) | |
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| Late (458.4–443.4 Mya) | |
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| | Llandovery (443.4–433.4 Mya) |
- Rhuddanian (443.4–440.8 Mya)
- Aeronian (440.8–438.5 Mya)
- Telychian (438.5–433.4 Mya)
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- Sheinwoodian (433.4–430.5 Mya)
- Homerian (430.5–427.4 Mya)
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| Ludlow (427.4–423.0 Mya) |
- Gorstian (427.4–425.6 Mya)
- Ludfordian (425.6–423.0 Mya)
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| Pridoli (423.0–419.2 Mya) | |
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| | Early (419.2–393.3 Mya) |
- Lochkovian (419.2–410.8 Mya)
- Pragian (410.8–407.6 Mya)
- Emsian (407.6–393.3 Mya)
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| Middle (393.3–382.7 Mya) | |
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| Late (382.7–358.9 Mya) | |
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| | Cisuralian (298.9–272.3 Mya) | |
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| Guadalupian (272.3–259.8 Mya) | |
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| Lopingian (259.8–252.17 Mya) | |
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| | | | | | kya = thousands years ago. Mya = millions years ago. * Not officially recognized by the I.C.S. |
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