The Ordovician is the second period of the Paleozoic era. It lasted from about 485.4 million years (mya) to 443.4 mya.[1] It follows the Cambrian period and is followed by the Silurian period.

The Ordovician was named after the Welsh tribe of the Ordovices. It was defined by Charles Lapworth in 1879. He recognized that the fossils in the disputed strata were different from those of the Cambrian or the Silurian. Therefore, he reasoned, they should be placed in a period of their own.

Recognition of the Ordovician period was slow in Britain, but elsewhere it was quickly accepted. In 1906 it was adopted as an official period of the Paleozoic era by the International Geological Congress.

The Ordovician ended with a series of extinction events that, together amount to the second greatest extinction of the Phanerozoic. This was the End–Ordovician extinction event.



Sea levels were high during the Ordovician. Shallow (<50 metres) inland seas were the greatest for which evidence is preserved in the rocks.

During the Ordovician, the southern continents collected into a single continent called Gondwana. Gondwana started the period in equatorial latitudes and, as the period progressed, drifted toward the South Pole. Early in the Ordovician, the continents Laurentia (present-day North America), Siberia, and Baltica (present-day northern Europe) were still independent continents.


The Ordovician was a time of calcite sea geochemistry in which low-magnesium calcite was the main marine precipitate of calcium carbonate.[2]

Other Languages
Afrikaans: Ordovisium
Alemannisch: Ordovizium
asturianu: Ordovícicu
azərbaycanca: Ordovik dövrü
Bân-lâm-gú: Ordovices-kí
беларуская: Ардовікскі перыяд
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oʻzbekcha/ўзбекча: Ordovik sistemasi
پنجابی: اورڈوویشین
Piemontèis: Ordovician
polski: Ordowik
português: Ordoviciano
română: Ordovician
Scots: Ordovician
slovenčina: Ordovik
slovenščina: Ordovicij
српски / srpski: Ордовицијум
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svenska: Ordovicium
Tagalog: Ordovician
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文言: 奧陶紀
Winaray: Ordovician
粵語: 奧陶紀
中文: 奥陶纪