The Canadian is the Lower or Early Ordovician in North America. The term is common in the older literature and has been well understood for more than a century. However it has no official recognition by the International Commission on Stratigraphy (ICS) and has been superseded by the more recently defined Ibexian series of western Utah.
8-716: 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. The Cassinian is named for the Fort Cassin Formation of Vermont. Rocks of Cassinian age are found in
16-517: A separate system would greatly solve problems in Early Paleozoic stratigraphy. As such, faunas in limestones of Canadian age are uniformly widespread and set off sharply from black shale graptolite facies (Flower 1957) whereas those in the remaining Ordovician are more local in nature and the two facies are more integrated. In common practice (e.g. MLK 1952, Weller 1960) the Canadian has been viewed as
24-683: A system separated from the rest of the Ordovician (Weller 1980), then known as the Lower Silurian, and referred to the rest of the Lower Silurian as the Trenton System. At that time the Ordovician had not yet been recognized. Later Ulrich redefined the Canadian as roughly equivalent to the Beekmantown strata of the Lower Ordovician. Flower (1957 p. 17) felt that recognition of the Canadian as
32-627: Is upper, or late Arenigian which is exactly equivalent to the newly proposed Floian , 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
40-575: 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. which may be short, looking at the El Paso section and Early Ordovician cephalopod evolution In worldwide terms the Cassinian
48-578: The Early, or Lower Ordovician. Flower however (1957, 1964) separated the Canadian from the rest of the Ordovician and defined it as a four-part system, divided in ascending order into the Gasconadian, Demingian, Jeffersonian, and Cassinian which stands today. The remaining Ordovician was also divided (Flower 1964, fig 3 p. 23) into four parts, the Whiterockian, Chazyan, Mohawkian, and Cincinnatian. Starting at
56-607: The Ibex region in western Utah, extends 2.7 .m.y. into the Cambrian taking up more than half of the Trempealeauan . The Cassinian is followed in North America by the Whiterockian 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. Canadian Epoch Dana introduced the Canadian as the name for
64-672: The bottom: All four stages of the Canadian, except for the uppermost Cassinian, are represented in the El Paso Group in New Mexico and West Texas. The name comes from the City of El Paso, Texas, which is next to the Franklin Mountains were the type section is found. The Ibexian and Canadian correlate imprecisely. Their upper boundaries are equivalent, found at the base of the Whiterock stage and
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