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Definitions of chronostratigraphic subdivisions in the Ordovician System

By
R. A. Fortey
R. A. Fortey
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Published:
January 01, 2000

Abstract

The base of the Ordovician has in the past been taken at the base of the Arenig Series in the British Isles, not least because Lapworth (1879, p.14) defined it that way – he recognized the System as comprising ‘Strata included between the base of the Lower Llandovery Formation and that of the Lower Arenig’. The base of the Arenig Series was taken as the lower boundary of the Ordovician System by Williams et al. (1972); hence Tremadoc rocks were excluded from the Ordovician correlation charts, and included in the Cambrian correlation charts by Cowie et al. (1972).In other parts of the world, for example in Scandinavia and the United States, an horizon at or close to the base of the Tremadoc Series had usually been considered to mark the base of the Ordovician. Henningsmoen (1973) discussed the history of these different usages, and noted that Lapworth himself entertained several views on where the base of the Ordovician should be taken, and indeed by 1902 (in Groom 1902, p.148) was evidently prepared to accept at least some part of the Tremadoc within his system.

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Contents

Geological Society, London, Special Publications

A revised correlation of Ordovician Rocks in the British Isles

R. A. Fortey
R. A. Fortey
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D. A. T. Harpe
D. A. T. Harpe
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J. K. Ingham
J. K. Ingham
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A. W Owen
A. W Owen
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M. A. Parkes
M. A. Parkes
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A. W. A. Rushton
A. W. A. Rushton
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N. H. Woodcock
N. H. Woodcock
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Geological Society of London
Volume
24
ISBN electronic:
9781862396920
Publication date:
January 01, 2000

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