Paleo Context, Relative Age, and Absolute Age

Documentation Trees
1

:open_book: This guide details how Specify 7 manages geological and paleontological time data. It covers the core concepts, definitions, and relationships between Paleo Context, Relative Age, and Absolute Age, as well as where to find these records in the database.

In paleontological and geological collection management, accurately capturing when an object was formed or deposited, how it relates to known rock layers, and how its age was measured is critical. Specify 7 handles this using three distinct yet interconnected constructs.

Relational Overview

flowchart TD
    CO[Collection Object] --> PC[Geo/Paleo Context]
    CO --> RA[Relative Age]
    CO --> AA[Absolute Age]
    PC -->|Refers to Chronostratigraphy| GTP[Chronostratigraphy Tree]
    PC -->|Refers to Lithostratigraphy| LS[Lithostratigraphy Tree]
    PC -->|Refers to Biostratigraphy| GTP
    RA -->|Links to Named Period| GTP
    AA -->|Derived using| DM[Dating Method / Citations]
    AA -.->|Calibrates / Refines| RA
    RA -.->|Validates / Constrains| PC

Paleo Context (Geologic Context)

  • What it is: A comprehensive aggregate container that anchors a specimen, locality, or collecting event to its broader physical and geological setting.
  • Role in Specify: Rather than holding a single numerical date, a PaleoContext record groups multiple stratigraphic trees together. It can be linked directly to CollectionObject, CollectingEvent, or Locality records.
  • Components aggregated:
    • Chronostratigraphy: Geologic time units (e.g., Eon, Era, Period, Epoch, Age) managed via the GeologicTimePeriod tree (shown in the interface as Chronostratigraphy).
    • Lithostratigraphy: Rock unit classifications (e.g., Supergroup, Group, Formation, Member, Bed) managed via the LithoStrat tree (shown in the interface as Lithostratigraphy).
    • Biostratigraphy: Biozone classifications based on fossil assemblages. This connects to nodes present in the GeologicTimePeriod that also have IsBioStrat indicated as true.
    • Tectonic Units: Structural or terrane unit definitions managed via the TectonicUnit tree.

Relative Age

  • What it is: An expression of where a sample falls within a chronological sequence relative to other rock layers or geological events, without providing an exact numerical calendar age.
  • Data Type: Categorical named time intervals (e.g., “Late Cretaceous”, “Early Miocene”).
  • Basis: Stratigraphic position, biostratigraphic biozones, or index fossils.
  • Role in Specify: Stored in the RelativeAge table and linked directly to a node on the GeologicTimePeriod tree via the AgeNameID field (and optionally AgeNameEndID for ranges).

Absolute Age

  • What it is: A quantitative, numerical age estimate (and error margin) determined through laboratory analytical methods.
  • Data Type: Quantitative numbers with possible error ranges.
  • Basis: Most commonly radiometric dating.
  • Role in Specify: Stored in the AbsoluteAge table. It captures numerical values (AbsoluteAge), margins of error (AgeUncertainty), dating methods (DatingMethod), and lab metadata.

How They Work Together

  1. Aggregation vs. Specific Determination:

    • A specimen’s general geological setting is captured under its linked PaleoContext record.
    • Specific determination events, such as a published radiometric date or a new biostratigraphic analysis, are recorded via individual AbsoluteAge or RelativeAge records linked directly to the CollectionObject or Component.

  2. Cross-Validation & Calibration:

    • Absolute Age calibrates Relative Age: Laboratory dates ((83.6\text{ Ma})) anchor relative time names (“Campanian”) to absolute chronological scales.
    • Relative Age constrains Absolute Age: Stratigraphic placement and index fossils help verify whether a laboratory-derived radiometric date is scientifically plausible or affected by sample contamination.

  3. Supporting Literature & Media:

    • Both RelativeAge and AbsoluteAge have dedicated citation tables (RelativeAgeCitation, AbsoluteAgeCitation) and attachment tables (RelativeAgeAttachment, AbsoluteAgeAttachment) to link directly to published literature or analytical lab reports.