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Key events in the Ordovician
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Key events of the Ordovician Period.
ICS approved stages.

Axis scale: millions of years ago.[2]

The Katian is the second stage of the Upper Ordovician. It is preceded by the Sandbian and succeeded by the Hirnantian stage. The Katian began 453.0 ± 0.7 million years ago and lasted for about 7.8 million years until the beginning of the Hirnantian 445.2 ± 1.4 million years ago.[3]


The name Katian is derived from Katy Lake (Oklahoma, USA).[4]


The GSSP of the Katian stage is the Black Knob Ridge Section in southeastern Oklahoma (USA). It is an outcrop of the Womble Shale and the Bigfork Chert, the latter containing the lower boundary of the Katian. The lower boundary is defined as the first appearance datum of the graptolite species Diplacanthograptus caudatus. This horizon is 4.0 m above the base of the Bigfork Chert.[5][6]


  1. ^ Wellman, C.H., Gray, J. (2000). "The microfossil record of early land plants". Phil. Trans. R. Soc. B 355 (1398): 717–732. doi:10.1098/rstb.2000.0612. PMC 1692785. PMID 10905606. 
  2. ^ Gradstein, F. M., ed. (2012). The Geologic Time Scale 2012. Elsevier Science Ltd. p. 504. ISBN 978-0444594259. 
  3. ^ "GSSP Table - Paleozoic Era". Geologic Timescale Foundation. Retrieved 2 December 2012. 
  4. ^ Bergström, Stig; Finney, Stanley; Xu, Chen; Goldman, Daniel; Leslie, Stephen (31 August 2006). "Three new Ordovician global stage names". Lethaia 39 (3): 287–288. doi:10.1080/00241160600847439. 
  5. ^ Goldman, Daniel; Stephen A. Leslie; Jaak Nõlvak; Seth Young; Stig M. Bergström; Warren D. Huff (2007). "The Global Stratotype Section and Point (GSSP) for the base of the Katian Stage of the Upper Ordovician Series at Black Knob Ridge, Southeastern Oklahoma, USA". Episodes 30 (4): 258–270. Retrieved 20 September 2012. 
  6. ^ "GSSP for Katian Stage". Geologic Timescale Foundation. Retrieved 2 December 2012. 
Preceded by Proterozoic Eon Phanerozoic Eon
Paleozoic Era Mesozoic Era Cenozoic Era
Cambrian Ordovician Silurian Devonian Carboniferous Permian Triassic Jurassic Cretaceous Paleogene Neogene 4ry

Coordinates: 34°25′50″N 96°04′29″W / 34.4305°N 96.0746°W / 34.4305; -96.0746