The Cassinian is the latest age of the
Canadian Epoch when thought of temporally and the uppermost stage of the Canadian Series when thought of stratigraphically. The Canadian, either as a series or as an Epoch is the name that has been given to the Lower, or Early, Ordovician in North America and has been applied worldwide.
[Flower, R. H. 1964. The Nautiloid Order Ellesmeroceratida (Cephalooda), Memoir 12, State Bureau of Mines and Mineral Resources, Socorro, New Mexico.][Moore, Lalicker, and Fischer 1952. Invertebrate Fossils, McGraw-Hill]
The Cassinian is named for the Fort Cassin Formation of Vermont. Rocks of Cassinian age are found in the Champlain Valley and among other places in North America in the Great Basin of Western Utah and Nevada, and in the uppermost El Paso Group in southern New Mexico and west Texas.
[
The Cassinian has been given a span of only 1.2 million years, with a range from 473 - 471.8 m.y.a.]
Geowhen[Teichert et al, 1964. Treatise on Invertebrate Paleontology Part K Mollusca 3, Teichert and Moore eds.]
In worldwide terms the Cassinian is upper, or late Arenigian which is exactly equivalent to the newly proposed Floian
The Floian is the second stage of the Ordovician Period. It succeeds the Tremadocian with which it forms the Lower Ordovician epoch. It precedes the Dapingian Stage of the Middle Ordovician. The Floian extended from to million years ago. The ...
, both spanning the same 6.8 million years.[ In the four part Canadian series, the Cassinian is late upper Canadian, preceded by the Jeffersonian, and is equivalent to the upper Blackhillsian stage of the Ibexian which has been sought to replace the Canadian as the Lower Ordovician in North America. However the Ibexian, named for the Ibex region in western Utah, extends 2.7 .m.y. into the Cambrian taking up more than half of the ]Trempealeauan
The Trempealeauan is the upper or latest stage of the Upper or Late Cambrian in North America, spanning about 4 million years from about 492.5 to 488.3 m.y.a., equivalent to the Fengshanian of China. The name comes from the Trempealeau Formation, ...
.[ The Cassinian is followed in North America by the ]Whiterockian
The Whiterockian, often referred to simply as the Whiterock, is an earliest or lowermost stage of the Middle Ordovician. Although the Whiterockian or Whiterock Stage refers mainly to the early Middle Ordovician in North America, it is often used in ...
and by the newer ICS Dapingian, given respective durations of 9.8 and 3.7 m.y. and in older chronologies [ by the 7.8 million year Llanvirnian.
]
''References''
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Paleozoic