Lordovig: Difference between revisions

Sea levels were high during the Ordovician; in fact during the Tremadocian, [[Transgression (geology)|marine transgressions]] worldwide were the greatest for which evidence is preserved in the rocks.

 

During the Ordovician, the southern continents were collected into a single continent called [[Gondwana]]. Gondwana started the period in [[equator]]ial [[latitude]]s and, as the period progressed, drifted toward the [[South Pole]]. The Early Ordovician was thought to be quite warm, at least in the tropics. As with North America and [[Europe]], Gondwana was largely covered with shallow seas during the Ordovician. Shallow clear waters over continental shelves encouraged the growth of organisms that deposit calcium carbonates in their shells and hard parts. [[Panthalassic Ocean]] covered much of the northern hemisphere, and other minor oceans included [[Proto-Tethys]], [[Paleo-Tethys]], [[Khanty Ocean]] which was closed off by the Late Ordovician, [[Iapetus Ocean]], and the new [[Rheic Ocean]].

 

Ordovician rocks are chiefly [[sedimentary]]. Because of the restricted area and low elevation of solid land, which set limits to [[erosion]], marine [[sediment]]s that make up a large part of the Ordovician system consist chiefly of [[limestone]]. [[Shale]] and [[sandstone]] are less conspicuous.

 

A major mountain-building episode was the [[Taconic orogeny]] that was well under way in Cambrian times.

 

 

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