Range_of_Dates/Times	Beginning_Geologic_Age	For geologic time if a Calendar_Date is not appropriate
Range_of_Dates/Times	Ending_Geologic_Age	For geologic time if a Calendar_Date is not appropriate
Single_Date/Time	Geologic_Age	For geologic time if a Calendar_Date is not appropriate
Beginning_Geologic_Age	Geologic_Age	For geologic time if a Calendar_Date is not appropriate
Ending_Geologic_Age	Geologic_Age	For geologic time if a Calendar_Date is not appropriate
Geologic_Age	Geologic_Time_Scale	Mandatory.  Name of a recognized geologic time scale.
Geologic_Age	Geologic_Age_Estimate	Mandatory.  An absolute age or an event or period name.
Geologic_Age	Geologic_Age_Uncertainty	Mandatory if applicable.  The error estimate for the geologic age.
Geologic_Age	Geologic_Age_Explanation	Mandatory if applicable.  Name or description of dating method.
Geologic_Age	Geologic_Citation	Optional, repeatable.  Bibliographic citation for age or method.