GeologicUnit

What is a GeologicUnit?

Conceptually, a GeologicUnit may represent a body of material in the Earth whose complete and precise extent is inferred to exist (e.g., North American Data Model GeologicUnit, Stratigraphic unit in the sense of NACSN, or International Stratigraphic Code ), or a classifier used to characterize parts of the Earth (e.g. lithologic map unit like 'granitic rock' or 'alluvial deposit', surficial units like 'till' or 'old alluvium'). It includes both formal units (i.e. formally adopted and named in an official lexicon) and informal units (i.e. named but not promoted to a lexicon) and unnamed units (i.e., recognizable, described and delineable in the field but not otherwise formalised). In simpler terms, a geologic unit is a package of earth material (generally rock).

Realizations

Data model	Concept name	Definition
OGC GeoSciML	GeologicUnit	Conceptually, a GeologicUnit may represent a body of material in the Earth whose complete and precise extent is inferred to exist (e.g., North American Data Model GeologicUnit, Stratigraphic unit in the sense of NACSN, or International Stratigraphic Code ), or a classifier used to characterize parts of the Earth (e.g. lithologic map unit like 'granitic rock' or 'alluvial deposit', surficial units like 'till' or 'old alluvium'). It includes both formal units (i.e. formally adopted and named in an official lexicon) and informal units (i.e. named but not promoted to a lexicon) and unnamed units (i.e., recognizable, described and delineable in the field but not otherwise formalised). In simpler terms, a geologic unit is a package of earth material (generally rock).
IFC	GeologicUnit	Same as OGC GeoSciML
DIGGS	StratigraphyObservation	Descriptions of ordered bodies of rock or soil, such as formations, biostratigraphic units or aquifers.
AGSi	agsiModelElement	In AGSi a model is collection of elements (agsiModelElement object) and this may include geological units, identified as such (or as a specialization) using the elementType attribute.

Specializations (Types of GeologicUnit)

Source	Type	Link	Definition
BRGM	Registry	https://data.geoscience.fr/ncl/GeolUnitType	This register lists all the geologic units.
CGI	Registry	https://cgi.vocabs.ga.gov.au/object?uri=http%3A//resource.geosciml.org/classifier/cgi/geologicunittype	This register lists all the geologic units.

• allostratigraphic unit

• alteration unit

• artificial ground

• biostratigraphic unit

• chronostratigraphic unit

• deformation unit

• excavation unit

• geomorphologic unit

• geophysical unit

• lithodemic unit

• lithogenetic unit

• lithologic unit

• lithostratigraphic unit

• lithotectonic unit

• magnetostratigraphic unit

• mass movement unit

• pedoderm

• pedostratigraphic unit

• polarity chronostratigraphic unit

Properties

PropertyName	Definition
Identifier	The identifier should have the same value as the corresponding GeoSciML MappedFeature identifier, if available.
Name	name is a display name for the GeologicUnit.
Description	description is a description of the GeologicUnit, typically taken from an entry on a geological map legend.
geologicUnitType	geologicUnitType contains the type of GeologicUnit (as defined in GeoSciML). To report an identifier from a controlled vocabulary, geologicUnitType_uri shall be used.
rank	rank contains the rank of GeologicUnit (as defined by ISC. e.g., group, formation, member).
representativeLithology	description of the GeologicUnit’s lithology, possibly formatted with formal syntax (see 8.9.2.3). The description can be language-dependent. To report an identifier from a controlled vocabulary, representativeLithology_uri shall be used.
representativeAge	description of the age of the GeologicUnit (where age is a sequence of events and may include process and environment information). To report an identifier from a controlled vocabulary, representativeAge_uri, representativeOlderAge_uri, representativeYoungerAge_uri shall be used.
numericOlderAge	a numerical representation of the unit’s older age in million years (Ma).
numericYoungerAge	a numerical representation (Primitive::Number) of the unit’s younger age in million years (Ma).
observationMethod	a metadata snippet indicating how the spatial extent of the feature was determined. ObservationMethod is a convenience property that provides a simple approach to observation metadata when data are reported using a feature view (as opposed to observation view).
source	If present, the property source:Primitive::CharacterString is human readable text describing feature-specific details and citations to source materials, and if available provides URLs to reference material and publications describing the geologic feature. This could be a short text synopsis of key information that would also be in the metadata record referenced by metadata_uri.
metadata_uri	If present, the property metadata_uri:Primitive::CharacterString contains a URI referring to a metadata record describing the provenance of data.
shape	The property shape:GEO::GM_Object contains a geometry defining the extent of the feature of interest.
positionalAccuracy	If present, the property positionalAccuracy:Primitive::CharacterString is a quantitative value (a numerical value and a unit of length) defining the radius of an uncertainty buffer around a MappedFeature (e.g., a positionalAccuracy of 100 m for a line feature defines a buffer polygon of total width 200 m centred on the line).
GeolFormation	ISO14689:2017
FaciesLithostratigraphy	The characteristics of a rock or a sediment unit that reflect its environment of deposition and allow it to be distinguished from rock or sediment deposited in an adjacent environment.
FaciesPetrophysics	A rock mass that can be recognized by its composition, structures or fossil content and mapped on the basis of those characteristics.

FAQ

What about Hydrogeologic Units?

They are a type of GeologicUnit and are described in https://github.com/opengeospatial/Geotech/wiki/HydrogeoUnit

GitHub issue

https://github.com/opengeospatial/Geotech/issues/7