GeoSciML: Enabling the Exchange of Geological Map Data
Bruce Simons
Eric Boisvert
Boyan Brodaric
Simon Cox
GeoScience Victoria
GPO Box 4440 Melbourne,
Victoria, 3001, Australia
Bruce.Simons@dpi.vic.gov.au
Geological Survey of Canada
490 rue de la Couronne,
Québec, G1K 9A9 Canada
eboisver@nrcan.gc.ca
Geological Survey of Canada
615 Booth St, Ottawa,
Ontario, K1A0E9 Canada
brodaric@nrcan.gc.ca
CSIRO Exploration & Mining
ARRC, PO Box 1130, Bentley
WA, 6102, Australia
Simon.Cox@csiro.au
Tim R. Duffy
Bruce R. Johnson
John L. Laxton
Steve Richard
British Geological Survey
Murchison House, W Mains Rd
Edinburgh, EH9 3LA, UK
trd@bgs.ac.uk
U.S. Geological Survey
954 National Center
Reston, VA 20192, U.S.A.
bjohnson@usgs.gov
British Geological Survey
Murchison House, W Mains Rd
Edinburgh, EH9 3LA, UK
jll@bgs.ac.uk
Geological Survey of Arizona
416 W. Congress St., #100
Tucson, Arizona, 85701, USA
steve.richard@azgs.az.gov
SUMMARY
The CGI data model working group have established an
initial geology data model and XML based exchange
language to accommodate geological map data, referred
to as GeoSciML. The language is based on prior work
carried out at North American, European and Australian
geological survey and research organisations. Unified
Modelling Language (UML) has been used as a design
aid for capturing the geological concepts and their
properties. The UML model has then been converted to
the GML-conformant GeoSciML.
The design of GeoSCiML meets the short-term goal of
accommodating the geoscience information presented on
geological maps, as well as being fully extensible to
include the full range of geological concepts covered by
the geosciences.
To demonstrate the ability of
GeoSciML to deliver data via web feature services, a
small subset has been selected as a testbed. This testbed
will deliver lithostratigraphic units, boreholes, faults,
contacts and compound materials from different national
geological surveys.
Key words: data exchange, geology data modelling,
GeoSciML, GML, Web Feature Services, XML.
INTRODUCTION
The exchange of geoscientific information has traditionally
been through hard copy media such as geological maps,
reports and papers. The content and style of geological maps
has often been left to the authors' or organisations' individual
preferences or standards, with the success of the information
transfer dependent on the skills of the user to 'interpret' the
intent of the mapmaker. With the development of web-based
data access interfaces, and increased requirements for
machine-based data exchange by geoscientific agencies, the
ability to interpret meaning is lost. Although standardised
formats for geoscience data have long been seen as a desirable
goal, the need for common models and encodings has assumed
a greater practical significance for this machine-based data
exchange.
The IUGS Commission for the Management and Application
of Geoscience Information (CGI) established an initiative to
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develop a harmonised geoscience data model and exchange
format based on GML (Geography Mark-up Language),
referred to as GeoSciML (GeoScience Mark-up Language).
These developments incorporate several novel aspects in
design of the data model and transfer format as well as the
technical procedures involved in their creation.
Predecessor projects have strongly influenced the
development of GeoSciML.
These include multijurisdictional activities by the North American Geologic Map
Data Model Steering Committee (2004) and Australian
Government Geologists Information Policy Advisory
Committee (2004), the CSIRO led eXploration and Mining
Mark-up Language (XMML) work (Cox, 2004) and individual
agency work at the British Geological Survey (Sen and Duffy,
2005), GeoScience Victoria (Simons et al, 2005), and the
BRGM. Growing awareness of the overlap between these
projects and the desire to minimise duplication led to
agreement on the formation of a working group to move
forward collaboratively on the development of a data model
and transfer format under the auspices of the CGI.
GeoSciML accommodates the short-term goal of representing
geoscience information associated with geological maps and
observations, as well as being extensible in the long-term to
other geoscience data. It is unique in its breadth of inputs and
content as it draws from many national geoscience data model
efforts. From these it establishes a common suite of feature
types based on geological criteria (geological units, geological
structures, fossils, geological relationships, earth materials,
geological fabrics) or artefacts of geological investigations
(specimens,
sections,
observations,
measurements).
Supporting objects, such as timescales and lexicons, are also
included so that they can be used as classifiers for the primary
objects.
The demonstration of the delivery of a subset of GeoSciML
via Web Mapping Services (WMS) and Web Feature Services
(WFS) has been undertaken by the CGI working group. This
'testbed' delivers an extensive suite of property information for
lithostratigraphic and lithodemic geological units, faults,
geological contacts and boreholes.
METHOD AND RESULTS
The specific objectives of the CGI working group are to:

develop a conceptual model of geoscientific information
drawing on existing data models;
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GeoSciML
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


Simons BA, Boisvert E, Brodaric B, Cox S, Duffy TR, Johnson BR, Laxton JL and Richard S
implement an agreed subset of this model in an agreed
schema language;
implement an XML/GML encoding of the model subset;
develop a testbed to illustrate the potential of the data
model for interchange;
identify areas that require standardised classifications in
order to enable interchange;
Standards
In order to benefit from emerging geospatial web-service
standards the focus is on GML-based XML data encodings for
the transfer format. The modelling framework used for
GeoSciML is based primarily on the Rules for Application
Schema from ISO/TC 211 (ISO 19109:2004). The rules assert
that geospatial information languages should be developed
and governed within domain-specific communities. They also
specify the term "feature" for a real-world object of interest.
Features are classified into types on the basis of a
characteristic set of properties. For example a "GeologicUnit"
is a feature type that has a rank, composition, morphology,
outcrop character, colour, etc.
base map depiction and extents to draw a geologic map
visualisation.
6. GeologicObject represents those geological concepts that
can be described in their own right and may be properties
of other geological concepts, but are not mappable
features. Rocks (which are considered as types of
CompoundMaterials) and fossils are two such objects.
A sample of the associations, and their roles, that exist
between various classes are shown in the summary diagram
(Figure 1) to illustrate the way that the model works. For
example a Fault can be made up of FaultSurfaces (role =
faultSurface) that may have one or more Displacement
attributes.
Complementing the ISO standards, GML has been developed
as an XML encoding for geographic information. GML
directly provides few concrete feature types, as these are
intended to be created using the standard components in a
domain-specific "GML Application Schema". GeoSciML is
an example of one of these schema.
Cox et al. (2004) established rules for converting models
expressed in UML to GML-conformant XML. These rules are
highly significant since they allow GML-compatible model
development to take place in the intuitive graphical UML
environment. They also ensure consistency of XML schema
derived from the UML.
The GeoSciML Model
Figure 1 shows a UML diagram of a summary version of
GeoSciML to illustrate the framework within which the data
model is being developed. Due to the complexity of the
model we have not shown all the classes. The attributes of the
various classes are also not shown.
Four top-level GML classes are used as starting points:
1. Abstract Feature is the root of all classes representing
real-world objects. These include GeologicFeatures,
representing geological concepts (GeologicStructures,
GeologicUnits), as well as artefacts of the evidence
collection process (Site, Observation etc) and artefacts of
the geologic record (MappedFeatures).
2. Abstract Geometry is the GML object that describes the
geometry of the features (eg. point, line, polygon).
3. Metadata is the root of all classes dealing with metadata,
including dataset metadata, mapped feature metadata and
geological feature metadata.
4. Definition is the root of classes representing the reference
systems, controlled vocabularies and dictionaries that
constrain the values of the class properties.
Two additional classes specific to GeoSciML inherit directly
from the top level AbstractGML class:
5. GeologicPortrayal stores the model elements used to
represent the selection and symbolization of
MappedFeature AbstractGeometry instances, along with
AESC2006, Melbourne, Australia.
Figure 2. UML diagram of GeoSciML GeologicUnit and
EarthMaterial classes, showing inheritance, associations
and roles, and class attributes, with data types and
cardinality.
The properties of geological units are shown in Figure 2.
These are the subset of properties that have been chosen for
testbed purposes. Like all classes in GeoSciML, geological
units (GeologicUnit) inherit a name, description and GML id
from AbstractGML. They also inherit an age and purpose
from GeologicFeature, in addition to the GeologicUnit
attributes bodyMorphology, outcropCharacter, genesis and
exposureColour. Only lithostratigraphic and lithodemic units
(types of LithologicUnits) are being considered as part of
testbed. Lithologic units have the additional attributes of
rank, composition, weatheringCharacter, the presence of
structures and metamorphicGrade. Lithostratigraphic units
include additional attributes to account for specific bedding
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Simons BA, Boisvert E, Brodaric B, Cox S, Duffy TR, Johnson BR, Laxton JL and Richard S
related properties. Other types of GeologicUnits (such as
Chronostratigraphic, Geomorphologic, Pedostratigraphic,
Lithotectonic) are accommodated by the model.
The
GeologicUnitPart class allows GeologicUnits to be made up of
other GeologicUnits (for example 'Formations' with child
'Members'). The CompositionPart class allows GeologicUnits
to be composed of CompoundMaterials, which in the model
represent either rocks or unconsolidated material.
GeoSciML also includes an extensive suite of data types
defined to accommodate the wide range of values that are
assigned to geological observations. These are designed to
accept single (eg fine grained) or range (eg fine grained to
medium grained) values from controlled vocabularies, single
or range numeric measurements with error values and units of
measures, or combinations of these.
seek broader geological community support for GeoSciML as
the standard geological map data exchange language.
Controlled Vocabularies
GeoSciML is designed to provide the mechanism that will
enable delivery of the geological and geographic information
associated with geological maps. A current gap in GeoSciML
is the lack of an agreed set of vocabularies for the data
content, limiting the ability to deliver standard data content.
Therefore, at present, GeoSciML provides a standard schema
but does not define standard content within the schema.
Future work involves developing agreed standards on data
content, that is controlled vocabularies, thesaurus and
dictionaries, by the international geological community. The
CGI are establishing a separate collaborative effort to meet
this need.
Testbed 2
CONCLUSIONS
The working group has established a testbed to demonstrate
the delivery of geological map data via the web using Web
Mapping Services (WMS), Web Feature Services (WFS) and
GeoSciML. This follows on from demonstrations using
XMML to exchange borehole data between the British and
French geological surveys (see https://www.seegrid.csiro.au/
twiki/bin/view/CGIModel/TestBed#CGI_Interoperability_Test
bed_1) and the SEEGrid geochemistry demonstrator (Cox et
al., 2005). The aim of Testbed 2 is to evaluate the ability of
GeoSciML to deliver the rich and complex data used to
generate geological maps from a variety of geological
organisations via WMS and WFS. The geological surveys of
Canada, USA, UK, Sweden, France and Arizona along with
Geoscience Australia, GeoScience Victoria and CSIRO are
participating in Testbed 2.
Testbed 2 aims to deliver 4 use cases using GeoSciML:

Use Case 1: Client asks for a map showing geological
units, faults, contacts and/or boreholes on a browser.
Server returns a map with default symbolisation. User
can click on any graphic feature from one layer to
retrieve at least an HTML presentation of the attributes of
that feature which is consistent with the CGI model.
(Client can request other formats than HTML if server
supports them.).

Use Case 2: Select mapped features by specifying a
geographic bounding box and download the most specific
information available for each mapped feature as
GeoSciML
GeoSciML accommodates the short-term goal of representing
geoscience information associated with geological maps and
observations, as well as being extensible in the long-term to
other geoscience data. It is unique in both the breadth of its
inputs and content. This has been achieved by drawing on
many local, national and international geoscience data model
efforts, in conjunction with the work on international data
exchange standards.
The working group has established a testbed to demonstrate
the delivery of geological map data from a variety of national
and state geological surveys using Web Mapping Services,
Web Feature Services and GeoSciML. The success of this
demonstrator will determine the future for XML-based
geological data exchange languages.
REFERENCES
Cox, S.J.D., 2004, XMML – a standards conformant XML
language for transfer of exploration data: Proceedings,
ASEG/PESA Geophysical Conference and Exhibition, Sydney
2004
Cox, S.J.D., Daisey, P.W., Lake, R., Portele, C. and
Whiteside, A., 2004, Geography Markup Language (GML)
3.1.0, OpenGIS® Recommendation Paper, OGC document
03-105rl, xxi+ 580.
Cox, S.J.D., Dent, A., Esterle, J., Woodcock, R., Girvan, S.,
Mackey, T., Wyborn, L., Bandy, S., Ward, B., Hannant, T.,
Jenkins, G., Jolly, M., Atkinson, R. and Barrs, P., 2005
Standardized Web-access to Geoscience Datasets: the
SEEGrid WFS Testbed. Proceedings of IAMG'05: GIS and
Spatial Analysis, Vol.2, 844-849.

Use Case 3: The user chooses to display mapped features
representing geologic units, symbolized on the basis of
age using the IUGS standard geologic age colour scheme,
or on the basis of lithology using a CGI defined lithology
colour scheme.

Use Case 4 (optional): Select a subset of geologic unit
mapped features on the basis of age or lithology and
highlight them with the same highlight colour.
Government Geologists Information Policy Advisory
Committee, 2004, National Geological Data Model Version
1.0 Explanatory Notes.
http://www.geoscience.gov.au/geoportal/standards.html
Testbed 2 aims to deliver these four use-cases using geological
data from a variety of organisations and map-scales as a
demonstration by September 2006. The testbed results will be
formally presented to the CGI during the IAMG conference in
September 2006 with the intention to showcase the results to
North American Geologic Map Data Model Steering
Committee, 2004: NADM Conceptual Model 1.0—A
conceptual model for geologic map information: U.S.
Geological Survey Open-File Report 2004-1334, 58 p.,
accessed online at URL http://pubs.usgs.gov/of/2004/1334.
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Also published as Geological Survey of Canada Open File
4737, 1 CD-ROM.
Sen, M. and Duffy, T., 2005 GeoSciML: Development of a
generic GeoScience Markup Language. Computers &
Geosciences, 31, 1095–1103.
Simons, B., Ritchie, A., Bibby, L., Callaway, G., Welch , S.,
and Miller, B., 2005, Designing and Building an Object–
Relational Geoscientific Database using the North American
Conceptual Geology Map Data Model (NADM-C1) from an
Australian Perspective. Proceedings of IAMG'05: GIS and
Spatial Analysis, Vol.2, 929–934.
Figure 1. UML diagram showing the primary hierarchy of a selection of GeoSciML classes and relationship to base classes
provided by GML, and a selection of associations between classes.
AESC2006, Melbourne, Australia.
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