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                            Middle Ordovician Epoch
                                    (Dyfed)
 
                     From 471.8 +/- 1.6 To 460.9 +/- 1.6 Ma
 
  Start Defined By:  Conodont, potentially lowest occurrence of Protoprioniodus 
     aranda or of Baltoniodus triangularis.
  End Defined By:  Graptolite, lowest occurrence of Nemagraptus gracilis.
 
  Start Based On:  Gradstein, Ogg, Smith, _A Geologic Time Scale 2004_
  End Based On:  Gradstein, Ogg, Smith, _A Geologic Time Scale 2004_
 
 -- Overlaps With --
  Australian Stage:     Chewtonian (473 - 471)
  North American Stage: Mohawkian  (462 - 451)
 
 -- A Substage of --
  Eon:    Phanerozoic (542 - -5.5012e-005)
  Era:    Paleozoic   (542 - 251)
  Period: Ordovician  (488.3 - 443.7)
 
 -- Preceeded By --
  Epoch:                Early Ordovician (488.3 - 471.8)
  ICS Stage:            Arenig           (478.6 - 471.8)
  Chinese Stage:        Dawanian         (472 - 471.8)
  European Stage:       Fennian          (473.5 - 471.8)
  North American Stage: Ibexian          (491 - 471.8)
  North American Stage: Cassinian        (473 - 471.8)
 
 -- Followed By --
  Epoch:            Late Ordovician (460.9 - 443.7)
  ICS Stage:        Ordovician V    (460.9 - 455.8)
  Australian Stage: Gisbornian      (460.9 - 456)
  Chinese Stage:    Baotan          (460.9 - 454.5)
  European Stage:   Aurelucian      (460.9 - 457)
  General Stage:    Caradoc         (460.9 - 449)
  Regional Stage:   Costonian       (460.9 - 459)
 
 -- Contains the Following Stages --
  ICS Stage:            Ordovician III (471.8 - 468.1)
  ICS Stage:            Darriwilian    (468.1 - 460.9)
  Australian Stage:     Castlemanian   (471 - 470)
  Australian Stage:     Ypeenian       (470 - 468.1)
  General Stage:        Llanvirn       (471.8 - 464)
  General Stage:        Llandeilo      (464 - 460.9)
  North American Stage: White Rockian  (471.8 - 462)
 

This page was automatically generated from the GeoWhen database (version 1.1.0).  Please read the introduction regarding the accuracy and reliability of this information.  Comments, corrections, and additions can be sent to geowhen@robertrohde.com.  References to published academic literature are preferred.

Introduction

Geologic Timeline
(No Stages)

Geologic Timeline
(With Stages)

A-Z Stage List

Regional Information

Download Files


2003-2005 GeoWhen Database
Prepared By Robert A. Rohde


This page was last updated on Tuesday, January 18, 2005.