ammonites

Harland 3: Subperiods (Ordovician)

 Interval Maximum correlate
Late/Upper Ordovician Ordovician

= Bala
Middle Ordovician Ordovician

= Dyfed
Early/Lower Ordovician Ordovician

= Canadian

Authorizer: J. Alroy   Enterer: J. Alroy

Continent: global   Rank of each interval: subperiod/system

Basis of scale: paleontological  

Reference: W. B. Harland et al. 1990

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