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Lithology Categories vocabulary

Also see LithologyCategoriesDiscussion


This is a vocabulary of controlled concepts to use in populating the lithology element in Rock and UnconsolidatedMaterial elements in GeoSciML instance documents. We have attempted to come up with a list with on the order of 100 concepts that provides broad coverage of lithology types, without becoming so large that it becomes difficult to use. The current version (200811) includes 148 categories. Based on experience through May, 2009, comments have been collected, and review is under way of proposed updates for a new version, planned for release in September 2009.


Development of new version 2010

Comments in the proposed updates document were discussed and changes adopted at Face to face meeting in Quebec, September 2009. Additional recommendations from OneGeology Europe WP3 group brought forward in November, 2009 were discussed at a face to face meeting between Kristine Asch and Stephen Richard in Tucson, AZ, Dec 14-17, 2009. The current release candidate for final approval is in CDTG Subversion repository. An owl encoding of the vocabulary is also posted for comment and review at CGI_Lithology.owl. The goal is to release the 2010 version of the vocabulary in mid-January to allow OneGeology Europe to move ahead. Please review and comment now. Post comments here, or e-mail to SteveRichard.

-- SteveRichard - 2010-01-08

Reviews from the WP3 group have been collected, analyzed, and recommendations for revisions to the SimpleLithology vocabulary have been forwarded to the CDTG. These are the documents for the proposed revisions. The most complex issue is the question of how to deal with 'marl/marlstone' -- impure carbonate sediments. This is discussed in marl/marlstone. Other proposed updates are summarized in proposed updates. The actual new language (including some editorial revisions) is in the spreadsheet SimpleLithology2009xx.xls. If you would like to submit comments, add them to the discussion on this page if you have TWIKI permission, otherwise, please send to SteveRichard.

-- SteveRichard - 06 Jun 2009

The SimpleLithology200811 version of the vocabulary is under review by the WP3 group for the OneGeology Europe project, following discussions at OneGeology Europe WP3 meeting, Garmisch-Partenkirchen, Germany, Feb 11-13, 2009. Review and discussion of the vocabulary is also underway in the National Geologic Map Database Project (NGMDB) in the USA in connection with development of a standardized data delivery package for geologic map information. Based on these and any other reviews and comments, the Task group will need to make recommendations with respect to a new version of the vocabulary by end July, 2009. Final approval of a new version will be requested at the steering committee meeting in Quebec in September, but hopefully we can have a final draft ready for use in August.

-- SteveRichard - 19 Feb 2009

Issues for discussion 12/2009

-- SteveRichard - 2009-12-18

Version 200811

Comments and Discussion

Please post comments to this discussion page or e-mail to SteveRichard. -- SteveRichard - 25 Feb 2008


In our legend we have some lithologies that don't appear in the scheme, like clay (argilla), marl (marna) and all the intermediate types between clay and carbonate rock (e.g. calcareous-marls, clayey-marls, etc.). Can those lithologies be added to the scheme? We have some loess deposits. What do you think about the possibility to add this term (loess deposits) to the scheme instead of classify them as sand or something else? -- Marco Pantaloni, APAT

Many of the mixed carbonate-clay rocks can be classified using either carbonate or siliciclastic principles, depending on your background and the purpose for which you are describing them. Can the concepts like 'clayey marl' be accurately defined without the use of adjectival qualifiers like 'clayey'? I note that this popular "geologists' shorthand" does not really communicate a discrete concept once you scratch the surface. As an example, marl has the following definition (GSAmerica Glossary of Geology; Pettijohn 1947):

"a term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay and calcium carbonate (...) specif. and earthy substance containing 35-65% clay and 65-35% carbonate"

So what concept does the term 'clayey marl' actually refer to? It could be:

  • an earthy, very fine grained sediment that has some carbonate in it
  • a marl with more than 50% clay (some percentage value above which 'clayey' applies as a subdivision of marl)
  • a marl with more clay than 65% (almost a marl but not quite, so is an associated concept)
  • any other way you might think to interpret the term.

If any or all of these concepts are meant by the term 'clayey marl', then we have a case for adding a new concept and defining its place in the hierarchy (which looks more like a semantic network all the time). -- LindaBibby - 19 Feb 2009


Loess implies both a lithology type based on grain size and consolidation(?), and a genetic origin--aeolian, related to glaciation. Loess deposit would be a type of GeologicUnit, represented through a ControlledConcept with a prototype pointing to a GeologicUnit element in which the lithology composition would capture the lithology type information, and eventProcess and eventEnvironment would capture eolian process and glacial environment. -- SteveRichard - 25 Jun 2008

I agree with your comments on loess. An analagous argument can be mounted for ignimbrite or turbidite as lithology categories. -- LindaBibby - 19 Feb 2009


Lignite is an important missing category. (from OneGeology Europe WP3 discussions) -- SteveRichard - 19 Feb 2009


Is there a better way to represent chalk than 'Calcareous carbonate rock' and 'grainstone', based on idea that chalk is basically a fine-grained cocolith grainstone. (from OneGeology Europe WP3 discussions) -- SteveRichard - 19 Feb 2009


Can greenstone be defined as a lithology category distinct from granofels (perhaps a subtype?), amphibolite, or other existing categories. (from OneGeology Europe WP3 discussions) -- SteveRichard - 19 Feb 2009

On the term greenstone, we have a separate problem - it can be quite specific, but usage differs around the globe:

IUGS subcommission (2007) recommend greenstone only as a restricted term: 'Old field term used from massive metamorphic or altered magmatic rock, i.e. a granofels, whose greenish colour is due to the presence of minerals such as actinolite, chlorite and epidote.' They also recommend more precise terms be used wherever possible, e.g. chlorite-epidote granofels.

Other uses:

  • mafic (basic) metavolcanic rocks in 'greenstone belts'
  • Cambrian metabasalts (Victoria)
  • greenschist
  • a variety of nephrite jade from New Zealand

In addition, Wikipedia claims that to qualify as greenstone the rock must have a schistosity or some foliation or layering, which makes classification as a subtype of granofels tricky.

I have no problem with any term being added to the vocabulary - as long as it can be associated with a clearly defined concept, and its relationships with other concepts are defined. I think this is central to the argument. APAT (or me, or anyone else) should be free to use whatever terms they want. What matters to me is that I can determine what they mean when they use those terms. -- LindaBibby - 19 Feb 2009

Mud, clay, silt

The 200811 vocabulary does not break mud size sediment into clay and silt categories. This distinction is important in hydrogeologic situations. GSC had to add clay and silt subtypes of mud for their Groundwater Information Network application. Should this be propagated to the CGI vocabulary?

-- SteveRichard - 19 Feb 2009

Materials formed in surficial environment

To allow composition description of units that are mapped/defined based on presence of materials formed in the surficial environment US NGMDB added terms for 'Rock formed in surficial environment', 'Weathered rock' and 'Residual Material,' in addition to Duricrust and Bauxite currently included in CGI 200811. CGI 200811 did not include these categories based on argument that protolith/precursor terms should be used. The problem is that units with composition described using one of these categories would have to map to CGI200811 'Unconsolidated material', which may not be a very accurate mapping.

Possible definitions:

Material formed in surficial environment—Material that is the product of surficial processes operating on pre-existing rocks or deposits, analogous to hydrothermal or metasomatic rocks, but formed at ambient Earth surface temperature and pressure. Includes duricrust of various sorts (silcrete, calcrete), Residual material (saprolite), and weathered rock.

Residual material--Material of composite origin resulting from weathering processes at the Earths surface, in the absence of significant epiclastic or chemical input, mostly involving removal of chemical constituents by aqueous leaching. Consolidation state is not inherent in definition

Weathered rock--Rock that exhibits observable properties due to environmental conditions at or near the Earth surface affected by the atmosphere or hydrosphere. Corresponds to McMillan and Powell (1999) weathered rock grades II, III, and IV. Grades V and VI in the McMillan and Powell (1999) scheme would be Residual material.

Is there a need for an explicit soil category, with a definition like " Mineral or organic matter on the surface of the earth that has been subjected to and shows effects of genetic and environmental factors of climate, biological activity, and contribution of material from the atmosphere. The material differs from the protolith material in many physical, chemical, biological and morphological characteristics." (Based on soil [soil] (b), p. 609-610, Neuendorf et al., 2005). This would be distinguished from Residual material by 1) absence of inherited structure from protolith; 2) addition of material from atmosphere; 3) biological contribution.

-- SteveRichard - 04 Mar 2009


Is this a necessary term. Could be viewed as an unusual rock type that is sufficiently represented by the Mylonitic rock or Phyllite category.

-- SteveRichard - 04 Mar 2009

1GE WP 3 Comment

WP 3 of OneGeology-Europe suggests 16 additional terms and 32 changes to existing entries for SimpleLithologyTerms. The SimpleLithology2009_rc.rdf document served as a work base for these suggestions. For better readability, we created different table sheets (Version2009xxChanges and Version2009_RDFChanges) within the attached SimpleLithology2009xx_1GE_WP_3.xls file to better follow the history of the OneGeology-Europe WP 3 changes and additions. We also included all skos / rdfs fields that we deemed relevant for this discussion.

-- KristineAsch - 2009-12-10

Hannover, 30.11. 09 OneGeology-Europe (1GE) Workpackage 3 Subject: Scientific/Semantic Data Specification and Dictionaries

From 2/11.09 – 5/11/09 a discussion with the Chair of the CGI Interoperability Working Group, the WP 3 Leader Kristine Asch, WP 3 members Marco Klicker and Chris Schubert took place in Hannover. The aim was to compare the WP3 Scientific/Semantic Data Specification to the CGI structure, vocabularies and definitions and suggest any changes to the CGI vocabulary required in order to make both vocabularies fully compliant. We are intending to provide the OneGeology-Europe data providers with a list of concepts drawn from the CGI vocabularies with definitions that are identical with those given in the CGI vocabularies. Where definitions depend on the definitions of other concepts higher in the hierarchy that we are not using then we will add the definitions of these into the definition of the lower level concept to ensure consistency with the CGI vocabularies. We intend to use the urns from the GeoSciML vocabularies for referencing concepts.

Our proposals for new concepts for SimpleLithology and some queries are listed below: These issues were addressed in face to face meeting with Kristine Asch and Stephen Richard, Tucson, AZ Dec 14-17, 2009. Decisions are included after comments (some were put in during meeting, rest by -- SteveRichard - 2010-01-08)

  • 1. In certain instances there are differences between the Simple Lithology spreadsheet (SimpleLithology2009xx.xls) and the rdf file (SimpleLithology2009_rc.rdf) eg tephrite/basanite etc as types of tephritoid are not in the spreadsheet. Similarly impure carbonate sedimentary rock has different definitions between rdf and spreadsheet. Should we assume in these cases that the rdf is always the definitive version?

Deprecated by SteveRichard, now called simplelithology2009xxdeprecateduserdf-skos.xls

  • 2. Some definitions are missing from the rdf eg tephrite

SteveRichard, KristineAsch (15. Dec. 09): rdf document fixed, definition was in dc:source property

  • 3. We suggest that komatitic rock be removed from the current ultramafic class and put in a new ‘High Magnesium’ class under ‘Fine grained igneous rock’. The ultramafic class could then be moved under the phaneritic igneous rock class. We think this would more closely reflect LeMaitre.

High magnesium igneous rock class added, komatiitic rock is child of that and of ultramafic rock.

  • 4. We think a new concept ‘tuffite’ should be added under fragmental igneous rocks, defined as a fragmental igneous rock that has been reworked by epiclastic processes (there seems to be no home for these at present).

SteveRichard, KristineAsch (15. Dec. 09): tuffite now directly under rock as new category. New definition: ” Rock consists of more than 50 percent particles of indeterminate pyroclastic or epiclastic origin and less than 75 percent particles of clearly pyroclastic origin. Commonly the rock is laminated or exhibits size grading. (based on LeMaitre et al., 2002);

new comment by SteveRichard (15. Dec. 09): “50 percent cutoff with epiclastic rock is in contrast with LeMaitre et al., but is used for consistentency with other sedimentary rock categories following the pattern that the rock name reflects the predominant constituent.Murawski and Meyer, 1998).….

  • 5. In the rdf Aplite is under glass rich igneous rocks. We think this should be under phaneritic igneous rocks as in the spreadsheet.
KristineAsch suggests (15. Dec. 09): new label for phaneritic rock: “Plutonic” ;

delete the Crystalline Rock category, keep 'phaneritic' to avoid genetic denotation of plutonic.

alter definition of phaneritic rock: “.. and igneous rock in which the framework of the rock consists of individual crystals that can be discerned with the unaided eye …”

  • 6. We think doleritic rock should be under phaneritic igneous rocks as it is in the spreadsheet. They are now under Igneous directly.

doleritic rock is defined as 'intermediate in grain size between basalt and gabbro...', thus is not always phaneritic. -- SteveRichard - 2010-01-08

  • 6a Quartz rich rocks should be phaneritic, as they are always igneous (are they, do you know anything else?) – done, they are under “phaneritic” now (KristineAsch 15. Dec. 09).

  • 7. We think the classes ‘exotic alkali igneous rock’ and ‘exotic alkaline rock’ are rather confusing and would suggest renaming the former to ‘kalsilic and melilitic rocks’

SteveRichard, KristineAsch (15. Dec. 09): done

  • 8. We think the classes Gravel, Sand and Mud should all be under Clastic sediments as in the spreadsheet.

SteveRichard, KristineAsch (15. Dec. 09): New categories of Mud-size, sand-size and gravel size are being defined, and mud, gravel, sand are returning to clastic sediments

  • 9. We had another long discussion about how to separate silt and clay!! We think it might be useful to have an alternative (additional) division of the Mud concept space by introducing new classes of ISOClay and ISOSilt (you can probably think of better names) to reflect the grain size limits given in ISO14688.

Decided to keep operational definition for now (claystone means 'no detectable silt'), and keep Wentworth scale for clay to maintain consistency with other categories. -- SteveRichard - 2010-01-08

  • 10. We think the term ‘Sapropel’ should be added to the organic rich sediment class defined as ‘An unconsolidated jellylike ooze composed of plant remains, most often algae’.

SteveRichard, KristineAsch (15. Dec. 09): done

  • 11. We are unclear what the ooze term includes apart from organic mud (in which case it should be under organic rich sediment). Carbonate and siliceous sediments appear to have other homes and what else is there?

SteveRichard, KristineAsch (15. Dec. 09): Ooze, siliceaous ooze and Carbonate ooze now under biogenic sediment, but also under mud sized sediments

  • 12. Conglomerate, Sandstone, Mudstone and Wackestone should be under clastic sedimentary rock as in the spreadsheet.

Follow pattern used for analogous sediment categories, add generic sandstone, generic mudstone, generic conglomerate defined strictly on grain size, while Conglomerate, Sandstone, Mudstone and Wacke are defined to be clastic. -- SteveRichard - 2010-01-08

  • 13. We would like to add the term ‘Wacke’ under clastic sedimentary rocks defined as ‘An impure sandstone with >10% argillaceous material’

SteveRichard, KristineAsch (15. Dec. 09): Wackestone is now Wacke, is under clastic sedimentary rock, definition altered to remove volcanolithic origin; concept does not exclude some fine-grained conglomerate types.

  • 14. We would like to add the term ‘Siltstone’ under the mudstone class defined as ‘A mudstone that consists of >50% silt sized grains’.

SteveRichard, KristineAsch (15. Dec. 09): done. Alternate label “silt-bearing mudstone"

  • 15. The definitions of claystone and silt bearing mudstone are not based on percentage compositions which seems inconsistent with what is done elsewhere.

Decided to stick with operational definitions for these, to recognize actual usage -- SteveRichard - 2010-01-08

  • 16. We think shale should be under the claystone class and include the fact that it should contain >67% clay sized particles in the definition.

there are many definitions of shale, with no apparent consensus of usage that precludes siltstone as defined in this vocabulary. Thus shale is a kind of mudstone. -- SteveRichard - 2010-01-08

  • 17. We think marlstone should be defined as a synonym for impure carbonate sedimentary rock.

Marlstone is included as an alternate label for impure carbonate rock, carbonate mudstone, and carbonate-rich mudstone. -- SteveRichard - 2010-01-08

  • 18. There are commonly used terms such as chert which fall within the concept space of less common terms used in the vocabulary, in this case ‘non-clastic siliceous sedimentary rock’. We think terms like chert could be defined as related terms and then used for retrieval with some caveat eg ‘Chert is a type of non-clastic siliceous sedimentary rock. All instances of non-clastic siliceous sedimentary rock have been retrieved’. This would require us to identify all such related terms and of course assumes the relationship in question is ‘contained within’. What do you think?

Chert and flint are included as 'seeAlso' terms under non-clastic siliceous sedimentary rock. See Use of SKOS for GeoSciML concept vocabularies for discussion of usage of related term, see also, alternate label and preferred label in the vocabulary documents. -- SteveRichard - 2010-01-08

  • 19. We suggest adding ‘Category for rocks generally named blueschist’ to the definition of glaucophane lawsonite epidote metamorphic rock.

done. Blueschist is alternate label for concept. -- SteveRichard - 2010-01-08

  • 20. We think impact metamorphic rock should be under the metamorphic rocks class.

impact metamorphic rock concept renamed 'impact-generated material', child of composite genesis material. Consolidation state is not specified in definition, and impact genesis is not consistent with definition of 'metamorphic' as defined for metamorphic rock concept. This places impact-generated material at same conceptual rank with fault-related material, material formed in surficial environment, metamorphic rock, and metasomatic rock. -- SteveRichard - 2010-01-08

  • 21. We suggest adding Anthracite to GeoSciML in the same group as coal..

Lignite, bituminous coal, and anthracite added as subtypes of coal. -- SteveRichard - 2010-01-08

  • 22. We suggest adding ‘siliceous ooze’ and ‘calcareous ooze’ into the ooze class with definitions of ????. These are needed for marine geology that OneGeology will contain in the future.

done -- SteveRichard - 2010-01-08

  • 23. For marine geology, and to a minor extent to 1GE, tholeiitic basalt is important, so we suggest adding this to the basaltic rock Class..

Tholeiitic basalt and alkali-olivine basalt added as subtypes of basalt, with an attempt made to define these concepts with sufficient criteria to distinguish them. The resulting definitions are more restrictive than the generally quite fuzzy characterizations that appear in petrology texts. -- SteveRichard - 2010-01-08

  • 24. We suggest adding ‘Gabbronorite’ and ‘Norite’ to the monzogabbroic rock class according to the Plag, Px, Hbl triangles from Streckeisen.

This opens a big can of worms that would lead to addition of another bunch of categories because it introduces categories that utilize mafic mineralogy, which would then need to convolve with the QAPF categories in Streckeisen fields 9 and 10. Avoid for now. -- SteveRichard - 2010-01-08

-- KristineAsch - 2009-12-17
Topic attachments
I Attachment Action Size Date Who Comment
1GE_WP3_suggestions.docdoc 1GE_WP3_suggestions.doc manage 28.5 K 17 Dec 2009 - 22:10 KristineAsch entire set of 1GE-WP 3 suggestions and discussions from Hannover 30th Nov. 2009
Discussion_of_Marl.docdoc Discussion_of_Marl.doc manage 37.0 K 07 Jul 2009 - 01:22 SteveRichard Discussion of problems with impure carbonate nomenclature, and proposal for changes
Lithology_compilation_with_discussion.xlsxls Lithology_compilation_with_discussion.xls manage 4641.5 K 22 Sep 2008 - 22:38 SteveRichard Compiled lithology terms with committee discussion
Recommended_revisions_to_CGI_SimpleLithology200811.docdoc Recommended_revisions_to_CGI_SimpleLithology200811.doc manage 39.5 K 07 Jul 2009 - 01:23 SteveRichard Recommendations for updates to Simple lithology vocabulary (not including Marl/marlstone)
SimpleLithology2009xx.xlsxls SimpleLithology2009xx.xls manage 191.0 K 06 Jun 2009 - 01:29 SteveRichard Spreadsheet with all changes on Version2009xxChanges tab
SimpleLithology2009xx_1GE_WP_3.xlsxls SimpleLithology2009xx_1GE_WP_3.xls manage 364.0 K 18 Dec 2009 - 00:41 KristineAsch Suggested additions to the CGI vocabulary of GeologicSimpleLithologyTerms by Kristine Asch, WP 3, OneGeology-Europe. Includes complete CGI list + additional terms which are marked in red
Topic revision: r21 - 07 Apr 2011, MarcusSen

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