Ordovician

Ordovician Period 485.4–443.8 million years aby PreЄ Є O S D C P T J K Pg N
Mean atmospheric O ₂ content ower period duration	c. 13.5 vol % (68 % o modren level)
Mean atmospheric CO ₂ content ower period duration	c. 4200 ppm (15 times pre-industrial level)
Mean surface temperatur ower period duration	c. 16 °C (2 °C abuin modren level)
Sea level (abuin present day)	180 m; risin tae 220 m in Caradoc an fawin shairply tae 140 m in end-Ordovician glaciations^[1]
Key events in the Ordovician This box: view talk edit -485 — – -480 — – -475 — – -470 — – -465 — – -460 — – -455 — – -450 — – -445 — – P a l e o z o i c Cambrian O r d o v i c i a n Silurian E a r l y M i d d l e L a t e Tremadocian Floian Dapingian Darriwilian Sandbian Katian Hirnantian ← First laund plant spores^[2] ← Ordovician meteor event ← Archaeocyatha extinction Key events o the Ordovician Period. ICS approved stages. Axis scale: millions o years ago.^[3]

The Ordovician is a geologic period and system, the seicont o sax periods o the Paleozoic Era.

References[eedit | eedit soorce]

↑ Haq, B. U.; Schutter, SR (2008). "A Chronology of Paleozoic Sea-Level Changes". Science. 322 (5898): 64–68. Bibcode:2008Sci...322...64H. doi:10.1126/science.1161648. PMID 18832639.
↑ 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.
↑ Gradstein, F. M., ed. (2012). The Geologic Time Scale 2012. Elsevier Science Ltd. p. 504. ISBN 978-0444594259.