# Metadata extensions for describing geologic time # suitable for use with the FGDC Content Standard for Digital # Geospatial Metadata and the Biological Profile of that # standard, which is being developed by the FGDC Biological # Data Working Group and the National Biological Information # Infrastructure. # # Formal grammar: # # Single_Date/Time = [Calendar_Date + (Time_of_Day)] | Geologic_Age # # Range_of_Dates/Times = # [Beginning_Date + (Beginning_Time) + # Ending_Date + (Ending_Time)] | # [Beginning_Geologic_Age + Ending_Geologic_Age] # # Beginning_Geologic_Age = # Geologic_Age # # Ending_Geologic_Age = # Geologic_Age # # Geologic_Age = # Geologic_Time_Scale # Geologic_Age_Estimate + # 0{Geologic_Age_Uncertainty}1 + # Geologic_Age_Explanation + # (1{Geologic_Citation}n) # # Geologic_Citation = # Citation_Information # # Version 1.1, 30-Aug-1999 Susan Stitt and Peter Schweitzer (USGS) Extension_Information: Name: Beginning_Geologic_Age Short_Name: beggeol Type: Compound Rule: Beginning_Geologic_Age = Geologic_Age Parent: Range_of_Dates/Times Child: Geologic_Age Definition: A name, code, or date for the beginning of an event or period in geologic time. Rationale: To provide the capability to completely and accurately describe the geologic dates relevant to a data set. Source: National Biological Information Infrastructure, USGS Biological Resources Division, FGDC Biological Data Working Group Extension_Information: Name: Ending_Geologic_Age Short_Name: endgeol Type: Compound Rule: Ending_Geologic_Age = Geologic_Age Parent: Range_of_Dates/Times Child: Geologic_Age Definition: A name, code, or date for the end of an event or period in geologic time. Rationale: To provide the capability to completely and accurately describe the geologic dates relevant to a data set. Source: National Biological Information Infrastructure, USGS Biological Resources Division, FGDC Biological Data Working Group Extension_Information: Name: Geologic_Age Short_Name: geolage Type: Compound Rule: Geologic_Age = Geologic_Time_Scale + Geologic_Age_Estimate + 0{Geologic_Age_Uncertainty}1 + 0{Geologic_Age_Explanation}1 + (1{Geologic_Citation}n) Parent: Single_Date/Time Parent: Beginning_Geologic_Age Parent: Ending_Geologic_Age Child: Geologic_Time_Scale Child: Geologic_Age_Estimate Child: Geologic_Age_Uncertainty Child: Geologic_Age_Explanation Child: Geologic_Citation Definition: A name, code, or date describing an event or period in geologic time, expressed either as an absolute date calculated using a named dating method, or as a relative date that is drawn from stratigraphy or biostratigraphy. Rationale: To provide the capability to describe the geologic dates relevant to a data set. Calendar dates as provided in the ISO 8601 dating system used in the standard CSDGM are not adequate to describe geologic time periods. Absolute geologic time is usually measured in "millions of years" before present, but may use different units and relative base times. Relative geologic time is measured by subdivisions of the earth's geology in an order based upon relative age, most commonly, vertical or stratigraphic position. The actual dating systems used in geologic studies often tie relative times measured through stratigraphy or biostratigraphy to a particular absolute time using radioisotope dating techniques, among others. As these methods for absolute dating have improved, the estimates of the dates for strata have changed, consequently, it would be inaccurate to record absolute dates in situations where relative dates were measured. This structure is provided as an optional alternative to the standard calendar dates provided by ISO 8601. Source: National Biological Information Infrastructure, USGS Biological Resources Division, FGDC Biological Data Working Group Extension_Information: Name: Geologic_Time_Scale Short_Name:geolscal Type: text Domain: "Absolute" "Geomagnetic Polarity Time Scale" "International Geological Time Scale" "Oxygen-Isotope" free text Parent: Geologic_Age Optionality: mandatory Definition: Name of a recognized geologic time scale. This includes "Absolute" as the name of the time scale for measuring geologic dates before the present and names of geologic dating systems that are arrangements of symbols or names in order of relative geologic time. Rationale: To provide the capability to completely and accurately describe the geologic dates relevant to a data set. Source: National Biological Information Infrastructure, USGS Biological Resources Division, FGDC Biological Data Working Group Extension_Information: Name: Geologic_Age_Estimate Short_Name: geolest Type: text Domain: free text Parent: Geologic_Age Optionality: mandatory Definition: Either an absolute geologic date or a relative geologic age name describing an event or period in geologic time based on the Geologic_Time_Scale. For example, "300 Ma" (300 million years before present) is a Geologic_Age_Estimate based on the "Absolute" Geologic_Time_Scale, "C28r" is a chron name from the Geomagnetic Polarity Time Scale, and "Maastrichtian" and " Jurassic" are names from the International Geological Time Scale. Since different relative geologic time scales are often not aligned, multiple geologic dates may need to be specified. For example, the Geomagnetic Polarity Time Scale chron "C29r", at the K/T boundary lies in both the Maastrichtian and the Danian stages from the International Geological Time Scale, thus if you were documenting this event using the International Geological Time Scale, both "Maastrichtian" and "Danian" should be included here. Rationale: To provide the capability to completely and accurately describe the geologic dates relevant to a data set. Source: National Biological Information Infrastructure, USGS Biological Resources Division, FGDC Biological Data Working Group Extension_Information: Name: Geologic_Age_Uncertainty Short_Name:geolun Type: text Domain: free text Parent: Geologic_Age Optionality: mandatory if applicable Definition: The error estimate for the geologic time. This should include the units of measure, a description of what the error estimate represents and how it was calculated. Rationale: To provide the capability to completely and accurately describe the geologic dates relevant to a data set. Source: National Biological Information Infrastructure, USGS Biological Resources Division, FGDC Biological Data Working Group Extension_Information: Name: Geologic_Age_Explanation Short_Name:geolexpl Type: text Domain: free text Parent: Geologic_Age Optionality: mandatory if applicable Definition: The name and/or description of the method used to calculate the Geologic_Age_Estimate. Detailed information about the method may be provided through references contained in the Geologic_Citation. Rationale: To provide the capability to completely and accurately describe the geologic dates relevant to a data set. Source: National Biological Information Infrastructure, USGS Biological Resources Division, FGDC Biological Data Working Group Extension_Information: Name: Geologic_Citation Short_Name: geolcit Type: compound Rule: Geologic_Citation = Citation_Information Parent: Geologic_Age Child: Citation_Information Optionality: optional Definition: Citation for works providing detailed information about any element of the Geologic_Age. For example, a publication describing the methodology used for carbon dating or describing the basic geologic time scale in more detail could be cited here. Rationale: To provide the capability to completely and accurately describe the geologic dates relevant to a data set. Source: National Biological Information Infrastructure, USGS Biological Resources Division, FGDC Biological Data Working Group