group
Enable an agent to recognise, compare and assess a geological group through its constituent formations, diagnostic rock properties, boundaries and documented regional usage.
Bundle → Layer → Finding → Questions Filled
5 bundles · 9 layers · 10 findings · 18 questions
Group definition and rank The published geological meaning of the group and the reason for aggregating its formations.
Name and definition
Connect the group name to its defining usage and subsequent revisions.
Operative group definition
Record the definition being applied, including regional and historical limits on its use.
- Which publication defines this group, and which revision governs the present interpretation? provenance
- Which older names are synonyms, and which refer to materially different successions? boundary
Aggregation and hierarchy
Explain the relationship between group rank and its constituent geological units.
Formation aggregation
Record constituent formations, any intervening subgroups and the geological justification for treating them together.
- Which formations belong to the group under the selected regional definition? definition
- What diagnostic association makes their aggregation useful, and is a parent supergroup recognised? boundary
Lithologic recognition The observations used to recognise the aggregate succession and distinguish neighbouring units.
Diagnostic association
Identify the combination of lithologic features that supports group membership.
Recognition tests
Separate decisive features from common but nondiagnostic attributes.
- Which combination of rock types, textures or sedimentary or volcanic structures supports assignment to this group? definition
- Which nearby succession could be mistaken for it, and what observable contrast distinguishes them? boundary
Variation and preservation
Assess how local changes and alteration affect recognition.
Recognition under change
Record where facies variation, weathering, deformation or metamorphism weakens the diagnostic evidence.
- Which observed variations remain compatible with the published group definition? boundary
- What additional observation would discriminate a changed expression of this group from a different unit? action
Contacts and regional architecture The group's bounding contacts, internal succession and changing regional expression.
Bounding contacts
Locate and justify the lower, upper and lateral limits.
Contact placement
Record boundary criteria and the evidence for their placement at each locality.
- What observable change or published convention places each boundary in the examined section? boundary
- Does an apparent termination represent a depositional contact, erosion, faulting or concealed continuation? boundary
Regional succession
Track spatial changes in formation membership, order and preserved thickness.
Local group expression
Maintain locality-specific successions and distinguish measured extent from inferred continuation.
- Which formations occur at this locality, and which are absent, replaced laterally or unobserved? measurement
- What thickness and extent are supported, and how were dip, fault repetition and incomplete exposure handled? measurement
Correlation and assignment Evidence connecting occurrences to the named group and controlling subsequent interpretation.
Reference and correlation evidence
Connect candidate occurrences to published sections and independently described observations.
Supported occurrence link
Record the evidential path from an occurrence to the adopted group definition.
- Which reference sections, field observations, core descriptions or geophysical records support this assignment? provenance
- Which links are directly observed and which depend on correlation across unexposed ground? boundary
Interpretation and next action
Qualify temporal interpretations and decide how to handle unresolved membership.
Assignment confidence
Keep conflicting evidence and the next discriminating investigation attached to the assignment.
- Which dated horizons constrain this occurrence, and what uncertainty remains when extending those constraints across the group? measurement
- Should the assignment be accepted, retained as tentative or rejected, and what observation would change that decision? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Check these first
Recalled without web access and unsourced; every item is a lead to verify.
- Which of these check these first hold for the sense of group this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Recalled without web access and unsourced; every item is a lead to verify.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of group this model covers, and on what evidence? provenance
Classifiers Filled
- Family
- Thing Registry
- Category
- Physical world and living systems
- Entry kind
- thing
- Plane
- PHY
- Domain
- PHY.PLC
- Other names and narrower kinds
- BookBrainz edition group, risk analysis group
What it is Filled
In geology, a group is a lithostratigraphic unit made up of two or more formations that share features, ranking above a formation and below a supergroup.
In scope
- Group-level lithologic recognition criteria
- Constituent formations and optional subgroup or supergroup relationships
- Upper, lower and lateral boundaries
- Geographic extent and regional variation in constituent units
- Published definitions, reference sections and revisions
- Evidence and uncertainty supporting assignment and correlation
Out of scope
- Chemical groups, periodic-table groups and mathematical groups
- Complete descriptions of individual formations, members or beds
- Geological time units and their formal boundaries
- Independent models of depositional environments or tectonic events
- Mineral-resource estimates and engineering suitability assessments
- Ownership, access permissions and extraction rights
Why it exists Filled
Enable an agent to recognise, compare and assess a geological group through its constituent formations, diagnostic rock properties, boundaries and documented regional usage.
Distinguishing features Filled
- A group aggregates two or more associated formations sharing diagnostic lithologic properties; thickness alone does not establish group rank. See the [International Stratigraphic Guide](https://stratigraphy.org/guide/litho).
- Recognition depends on rock properties and stratigraphic relationships rather than a shared age alone. See the [International Stratigraphic Guide](https://stratigraphy.org/guide/litho).
- Regional changes in constituent formations do not automatically imply a different group. See the [International Stratigraphic Guide](https://stratigraphy.org/guide/litho).
- The name must denote a geological unit at group rank, rather than an arbitrary collection of rock samples or a mineral classification.
What robots and AI may and may not do Filled
Must not
- Treat a group name used in one region as valid in another without checking.
- Confuse a lithostratigraphic group with chemical, periodic-table or mathematical groups.
- Misreport stratigraphic data used for resource, water or hazard decisions.
Only with a human decision
- Relying on stratigraphic interpretation for drilling, mining or groundwater decisions.
May
- Describe a geological group and its constituent formations from stratigraphic sources.
- Correlate group boundaries across regions with the evidence and authority used.
Moral aspects Filled
- Geological maps guide water supply, construction and mining that affect communities.
- Inconsistent names cause costly misinterpretation.
Who is affected
- Geologists and engineers
- Communities affected by resource decisions
Owners Filled
Steward
Nobody owns it; geological surveys and stratigraphic commissions define and record names.
Master systems
- National geological survey stratigraphic lexicons
Links to other meta-models Filled
parent
- Q3550897 - registry parent class
What else AI and robots need to interact with it Filled
Identity and identifiers required Filled
- Vercy registry: vr.tr.group-q824979
- Wikidata: Q824979 (https://www.wikidata.org/wiki/Q824979)
Direct properties required Filled
- Published name and nomenclatural standing: Name plus formal, informal, superseded, disputed or unresolved status, qualified by authority and date
- Constituent formations: Formation references with stratigraphic order, applicable region and definition version
- Diagnostic lithologic association: Described combinations of rock types, textures, structures and distinguishing contrasts
- Boundary expression: Sharp, gradational, intertonguing, unconformable, fault-truncated, concealed or unresolved, separately for each contact
- Geographic occurrence: Mapped outcrop and subsurface occurrences with coordinate reference system, scale and confidence
- Local stratigraphic thickness: Metres, with locality, method, uncertainty and true-versus-apparent thickness designation
- Reference-section relationship: Published type or reference locality and section identifiers with their stated roles
- Age constraints: Ma with uncertainty, dating method and sampled horizon, or explicitly qualified relative-age constraints
Recognition required Filled
- A mapped group encompasses two or more formations rather than a single rock bed.
- Its constituent formations share documented lithological features while remaining individually distinguishable.
- Identification depends on the published regional definition and mapped boundaries because appearance alone does not establish stratigraphic rank.
Capabilities and actions required Filled
- Evaluate whether a section or borehole interval is a supported, tentative or rejected assignment to a named group.
- Assemble the applicable regional succession of constituent formations.
- Compare competing boundary placements against their lithologic evidence.
- Trace supported correlations between outcrops and subsurface records.
- Identify outdated names or memberships in a geological dataset.
- Recommend observations needed to resolve a specific assignment or correlation.
Hazards and failure modes required Filled
- Miscorrelation of strata across regions.
- Ambiguous use of the word group across sciences.
Standards and interfaces required Filled
- International Stratigraphic Guide, International Commission on Stratigraphy of the International Union of Geological Sciences.
Context of use required Filled
- Geological groups are used in geological maps, stratigraphic columns and regional descriptions to organize related formations.
- They support regional comparison and communication about rock successions whose constituent formations share diagnostic lithological features.
Sources Filled
- Wikidata item Q824979: group - identity and sense of the item
- Wikipedia: Group (stratigraphy) - general description of the item
Open questions
- Does an existing Vercy world model already cover lithostratigraphic groups, requiring this registry entry to link to it?
- Which national or regional stratigraphic codes must the model accommodate, and where do their group-rank conventions differ?
- How should historically named groups with poorly resolved constituent formations be represented without implying verified formal standing?
- What evidence thresholds should distinguish supported, tentative and rejected assignments in outcrop and subsurface settings?
- Which published examples best test regional membership changes, disputed boundaries and strongly altered successions?
Machine files
Provenance
thing registry research (pass 2) · unreviewed
Built from: models/things/publications/thing-q824979/spec.json