Layering

Lineation

Foliation

Fault (with attribute Displacement)

Fold

Fracture (example Joint)

The same geologic thing can be seen as more than one of these types.

Properties of GeologicStructure

GeologicAge

Genesis (history)

Pervasiveness

GeometricDescription (orientation, thickness, planar/linear, fold wavelength, ...)

Extent

GSDefiningElement (what makes the structure what it is)

discontinuity

shapedsurface

orientedParticle

materialboundary

layer

GeologicStructures may be described as compound; structures can be made up of structures.  In the diagram, CompoundGeologicStructure consists of one or more GeologicStructures.  Fabric is a CompoundGeologicStructure.  [Should we add an attribute for the relationship between a CompoundGeologicStructure and its component GeologicStructure(s)?]

There was an extended discussion attempting to classify geologic structures in a hierarchical way (e.g., penetrative vs discrete; planar vs linear; rock forming vs rock modifying), but none of these satisfied our constraints of simplicity and logic.  We consequently resolved to use a relatively flat structure.

GeologicProcess

Processes include the following types:

HydrothermalAlteration

Crystallization

Deposition (Example: Sedimentation)

Erosion

Intrusion

Volcanism

Metamorphism

Diagenesis

Metasomatism

Deformation

(possibly others ...)

Each GeologicProcess has one or more GeneticEvent; the ordered set of GeneticEvents comprises the Genesis (history).  Each GeneticEvent has a GeologicAge and a GeologicEnvironment (which remains unspecified at this point but is construed broadly).  The history of EarthMaterials and GeologicUnits are types of Genesis.  GeneticEvents might be thought of as at least partially overlapping, but the diagram says that the set of GeneticEvents comprising a Genesis is ordered. We recognize that GeneticEvents are typically continuous rather than discrete (instantaneous) but suspect that this arrangement will suffice for most probable uses.  It may be inadequate for use in simulation.

GeologicRelation

This concept allows us to link any GeologicConcepts to any others. We recognize several specific types of relationships for illustrative purposes:

StratigraphicRelation

IntrusiveRelation

StructuralRelation

SpatialRelation

TemporalRelation

(probably others ...)

More than two GeologicConcepts can be described in the same GeologicRelation; each has a GeologicRole in the relationship. The GeologicRole would have a vocabulary including terms like "overlies", "is overlain by", "is younger", "is older", "intrudes", "is intruded by", and so forth.

Question raised by Eric: Does the model distinguish between things we know don't exist and things we don't know exist? [Steve: at this point it seems that this is not explicitly represented. An ExistentialConfidence attribute may be useful. The confidence in existence of some phenomena is subjective…]

Jordan: It seems like almost all of the information on the map could be described by this relationship mechanism. Steve: I think you’re right, but this would be a meta model; in making a schema for a particular model, we make statements about which relationships are important enough to represent explicitly.

Boyan:  We don't expect general relationships among spatial objects to be described explicitly with this mechanism, but to be encapsulated implicitly by the geometry inherent in the spatial objects themselves. But because some ways of transferring spatial objects don't include topological relationships, so at least some topological relationships may be described explicitly where that meaning is significant from a scientific perspective.

ControlledVocabulary

This provides a way to specify the terminology associated with concepts and the relationships among both the concepts and the terminology.  Many names can be associated with a concept; one is designated as preferred in order to facilitate communication and consistency in the database.

GeologicTimeScale and LithologicClassification are types of ControlledVocabulary, but there are many other kinds not specified here.

The ControlledVocabulary may describe a formal standard or any individual's [self-consistent] usage of terms; it is not restricted to formally-published vocabularies.

Note that the metadata associated with a concept would include the source of a given term.

Here GeologicRelation subsumes generic relationships such as broader, narrower, precedes, follows, that are found in formal thesauri and in ordered sets.

GeologicProperty

This general class exists to allow the properties of geological things to have all of the properties and behaviors inherent in GeologicConcept (metadata, for example??).

The properties appear elsewhere in the model with appropriate roles (implicit or explicit).

Boyan would like to map the properties defined by GEON to those we have defined here.  Bruce notes that our list is likely to be incomplete because we simply haven't fleshed out the model to the fullest level of detail.

GeologicPortrayal

The clearest motivation for this concept is the need to describe presentations [Steve: isn’t portrayal explicitly concerned with visual presentations? Why not use the term visualization?] of geologic concepts, either as information derived from the database or as information supplied to the database (so that, for example, authors of geologic maps used to populate the database can recognize that their work has been fairly represented in the database). Steve: another important reason to record individual visualizations of data from the database is that maps (visualizations, presentations…) are designed by a geologist to communicate a particular understanding of the geology, and the choice of what to symbolize, and how it is symbolized has a significant impact on how the map communicates. Different visualizations based on the same data might communicate different aspects of the geology.

Subtypes of GeologicPortrayal include

Correlation Chart

Cross-section

GeologicMap

GeologicGraphic

GeologicPortrayal may have one or more associated Graphics, which may be GeologicGraphics or CartoGraphics. GeologicGraphics are graphics in which the spatial arrangement of elements in the graphic has some correspondence with the spatial arrangement of features in the Earth (a mapping…, i.e. could be georeferenced). CartoGraphics are graphics in which the arrangement of the elements is not a mapping (in the technical sense) to spatial arrangement in the earth, but may follow some other logic related to spatial or temporal relationships. A Cross-section and a GeologicMap are geologicGraphics. Correlation charts, explanations of map units, ternary diagrams to show composition are all CartoGraphics.  (Some parenthetical definitions would be helpful here, but I can't remember what these mean).

Each GeologicMap has an associated MapDescription which is the conceptual set of spatial objects, their classification, and symbolization for a particular geologic horizon, scale and projection.  A Cross-section (which is considered a special kind of geologic map in a vertical plane) will generally also have a MapDescription.

MapDescription consists of a set of spatial objects, symbols, and the meanings of the symbols.  The Legend associates symbols with meanings (concepts). Some symbols may be unique to a particular occurrence, for example if a particular mine of special interest is given a unique symbol, different from other mines on the map.

The MapDescription has associated Extents, Scale, Projection, BaseMap, and Horizon. BaseMap refers to the actual graphical image that provides geographic and cultural reference for the geologic occurrences displayed in the visualization. Extent describes the boundary of the region displayed in a visualization. Scale and projection determine the mathematical relationship between locations in the visualization and locations in the Earth. Horizon refers to the surface on which features are mapped, commonly surface topography, but also may be a vertical surface (cross-section), a horizontal surface (mine level), an unconformity, a fault surface (fault cut-off map), etc.... Most lines on a geologic map represent the intersection of 3-D geologic surfaces with a map horizon. A BaseMap typically relates to a single map horizon, but geologic lines on the map may be related to more than one map horizon. For example, structure contours represent the intersection of a geologic surface with multiple horizontal map horizons at different elevations, all of which are probably different from the map horizon of the BaseMap on which they are displayed.

The Legend consists of the explained symbols both of GeologicClasses (which summarize many occurrences) and individual occurrences. SpatialObjects are associated only with Occurrences, not with GeologicClasses.

Each SpatialObject is associated with a projection, scale, and horizon (which refers to the surface on which the feature is mapped [possibly a volume in 3-dimensional models]).

Boyan is concerned that the things comprising the MapDescription need to be defined as types of something else.  There is an ongoing argument about the terminology associated with the box labeled "GeologicClass".

Steve—we need clear definitions of what Occurrence, GeologicClass, and GeologicConcept are supposed to mean.

There is a conceptual distinction between the horizon defined for mapping features and the plane (or volume) in which the features are portrayed graphically.

It is possible that MapDescription could be used to describe portrayals of the other relationships (for example stratigraphic) among concepts in, for example, correlation charts and other diagrams that are not in a strict sense maps.