Do we need commissions in Belgium ?
National Commission of Stratigraphy ( NCS)
Do we need commissions in Belgium ?
Noël Vandenberghe, Marleen De Ceukelaire, Eric Goemaere (Geologica Belgica congress, 02/2016)
Commissions have a bad connotation in the scientific community because they are associated with the evils of bureaucracy. Therefore the board of the National Commission of Stratigraphy (NCS) has taken the opportunity of the 5th International Geologica Belgica meeting 2016 in Mons to present the NCS to the scientific community and to make clear that the NCS does contribute to their scientific activities.
These days, stratigraphy consists of a suite of modern subdisciplines. This is the result of a rapid evolution in the last half a century of stratigraphic practice. In the beginning of the second half of the 20th century geologists realized that the till then classical chronostratigraphic approach of ranging each unit in a time slot had serious shortcomings. Indeed diachronous deposits and the common occurrence of lateral lithological facies were recognized. The remedy was worked out in 1976 by Hollis. H. Hedberg who chaired the International Subcommission on Stratigraphic Classification at that time: he proposed to treat lithostratigraphy, biostratigraphy and chronostratigraphy separately. Although this is an efficient methodology, also today, the splitting into components, went much too far and almost killed stratigraphy as a science. One year after the publication of the Hedberg’s stratigraphic guide, the seismostratigraphy concept was released by industry bringing a new basin-wide perspective to stratigraphy. Afterwards, the same industry team spent a decade in sedimentary basins reputed for cyclicity to find out the sedimentological significance of the surfaces they systematically could identify in seismic sections. This resulted in the development of sequence stratigraphy in a monumental paper commonly known as the Haq et al. (1987) chart. Sequence stratigraphy reintegrated all stratigraphic disciplines into a new concept and suggested a genetic model with relative sea-level as a main controller in the shaping of stratigraphic sequences. The new concept revitalized stratigraphy and stimulated stratigraphers to go in ever increasing time resolution. Cyclostratigraphy for example became better understood and became the basis for the astrochronostratigraphic approach which today forms the backbone of the Cenozoic time scale. The renewed stratigraphic research has now firmly established component disciplines as litho-, bio-, chemo-, magneto-, cyclo- , astro-, chrono-, climate- ….stratigraphy.
While all these component disciplines can and need to be integrated in the stratigraphy of an area, it is imperative for communication that each of these component disciplines uses well defined concepts, units and boundaries between units. This is by no means easy to do as it requires a thorough understanding of a particular field of stratigraphy and an objective and detailed analysis of data and arguments. In addition, definitions need to be stable for a reasonable time. An example of a failure in this last respect was the introduction by the then existing Geological Council in 1929-1932 of a new General Legend for the detailed geological map of Belgium: this new legend was not linked to new maps and therefore was not widely followed as the earlier geological maps and their legend continued to be used. For all these reasons, the challenge of making the necessary definitions in stratigraphy is best taken up by a core of experienced stratigraphers, a task-group or commission.
Also, it should be realized that however specialized the different modern stratigraphic components are, lithological units remain the starting blocks of any further specialized analysis. Without well defined lithological units and their boundaries, no valid correlations between sections can be made and the exploitation of geological data bases becomes less reliable as they contain information by many geologists trained in different times and in different schools.
Chronostratigraphic definitions are of international concern as they need to be similar in any part of the world. They are taken care of by the International Commission on Stratigraphy (ICS) (www.stratigraphy.org), installed by the International Union of Geological Sciences (IUGS). The ICS works through subcommissions for the different Systems/Periods. Subcommissions have an elected board and maximum 20 selected voting members, serving a maximum of 3 terms of 4 years between successive International Geological Congresses. Subcommissions identify the issues to be addressed and install Working Groups for their study. Working Groups can remain active during many years. During the past decades, a main task of ICS has been the definition of GSSP’s (Global Boundary Stratotype Section and Point ) of all stages. The International Devonian subcommission for example has already completed this task and is at present concentrating on issues like the possibility to introduce substages because some biozones have a shorter range than the time interval of the stages in which they occur, like the correlation of GSSP’s from the marine realm to terrestrial environments, like the global significance of environmental crises, like the use of non-biological methods, like improving the timescale….
The occurrence of lithostratigraphic units is constrained by the extension of its sedimentary basin. Therefore lithostratigraphic definitions have a national or regional dimension. In many countries National and Regional Geological Surveys therefore play a leading role in lithostratigraphic studies. Data relevant for lithostratigraphy are acquired during mapping programs, during university type research and during sometimes very detailed local studies for applied projects. Because sedimentary basins are arbitrarily cross cut by national and regional boundaries, unfortunately lithostratigraphic traditions have also developed independently in neighbouring countries. Therefore efforts have to be made now to develop transnational and transregional cooperation in homogenizing lithostratigraphic definitions and nomenclature. This can be done in scientific international correlation programs, at the occasion of applied programs like the joint exploitation of cross-border groundwater resources or organized by geological surveys. The variety of sources for lithostratigraphic data and the variety of types of data collected make the existence of a review and reference body or commission necessary to achieve lithostratigraphic definitions and nomenclature. Geological Surveys are the natural bodies to take initiatives in the field of lithostratigraphy.
The National Commission for Stratigraphy (NCS) in Belgium is installed by the National Committee of Geological Sciences (NCGS) which itself depends on the Royal Academies as the international contact to IUGS. The Belgian National Commission for Stratigraphy (NCS) has the mission to deliver the standards and references for the lithostratigraphy in Belgium; in addition NCS informs about the status of the published national bio- and chronostratigraphy. At present at the NCS website, the basis for this information on the chronostratigraphy is the Geologica Belgica (2006) Volume9-N°1-2: Chronostratigraphic units named from Belgium and adjacent areas (edited by L. Dejonghe), while updates of this bio- and chronostratigraphic information are in progress.
The communication with the national and international geological community is realised by the NCS website ‘ ncs.naturalsciences.be’ (contact: webmaster Marleen De Ceukelaire). News from the NCS is published monthly in the Miscellanea of Geologica Belgica. The NCS is structured in the following subcommissions: Lower Paleozoic, Devonian, Carboniferous, Permian-Triassic-Jurassic, Cretaceous, Paleogene-Neogene and Quaternary. The NCS consists of a chairperson and two secretaries including the webmaster, the chairpersons and secretaries of each subcommission and representatives of the Flemish Community and the Région Wallonne. The subcommissions can install working groups as was done for example by the Paleogene-Neogene subcommission to review the Ieper Group and recently an elaborate ‘discussion’ text on the Ieper Group is published on the website.
A precise procedure is followed to introduce lithostratigraphic units and to decide on definitions. The starting document for the lithostratigraphy of Belgium is the Geologica Belgica (2001) Volume 4-N°1-2: Lithostratigraphic scale of Belgium (edited by P. Bultynck & L. Dejonghe). This document was established at the formation level. At present NCS examines necessary adaptations at this formation level and complements the lithostratigraphy at the member and bed levels. Subcommissions, eventually helped by working groups, post ‘discussion’ texts on the website which after revision into formal ‘propositions’, can be ratified by the NCS. All ‘discussion’ and ‘proposal’ texts are subject to public reactions which have to be dealt with before ratification becomes possible. The procedure is explained in detail on the website. To further ensure transparency, the full lists of the NCS members and of the members of all subcommissions and working groups are available at the website.
All ratified proposals are added to the NCS website, entry ‘lithostratigraphy’. To acknowledge the contribution for the entry of new data and for each modification, the authors of each new or modified unit are mentioned together with the date of ratification. Therefore it is perfectly possible to refer to such contributions in the bibliography of scientific papers; the elaborate procedure of discussion, proposal, public consultation and final ratification can be considered as a valuable scientific review as requested by scientific papers.
Aside entries on the website to all subcommissions, there is also an entry ‘RegWal’ describing units used in the legends of the new 1:25.000 Carte Géologique de la Wallonie; this special category is an intermediate step between the publication of the geological map legends and the more time consuming procedure of public discussion and ratification required by the NCS procedures. It is a task of the NCS to catch up within reasonable time but in the mean time the terminology of these map legends is also accessible through the NCS website. It can be noted in this context that several of the earlier ‘assises’, used as stratigraphic units by Asselberghs (1946) in his ‘L’éodévonien de l’Ardenne et des regions voisines’ (Mémoire de l’ Institut Géologique de l’ Université de Louvain, 16, 598 p), can be further useful as modern lithostratigraphic entities especially in the Neufchâteau syncline.
On the website, all ratified lithostratigraphic units, the original ‘2001’ formations, the modified formations , and new members and beds are listed in the appropriate stratigraphic order and their full description can be directly accessed. This is also the case for the ‘RegWal’ units. In addition all these units are also listed alphabetically to make an easy search possible even if no further chronostratigraphic positioning of a particular term is known.
Recently the tag ‘Alterations units’ has been added to the website to allow the formal description of units which have a clear in situ alteration origin and are lithologically different from their parent strata, as for example the Clay-with-Flint Formation.
Subcommissions further have the task to organise appropriate cross-border homogenisation, to describe the evolution of the stratigraphic terminology, by area and by author, and to inform on the present status of biostratigraphy, chronostratigraphy, sequencestratigraphy in their stratigraphic time interval.
This brief overview of the tasks of stratigraphic commissions and their rigorous procedures has intended to demonstrate the utility and even necessity of such commissions. International commissions provide chronostratigraphic standards while is the national and regional commissions provide standards for lithostratigraphy. The nature of lithostratigraphy and the tradition of having national or regional lithostratigraphic scales makes cross-border consultation imperative. National and Regional Geological Surveys are the natural promotors and coordinators of lithostratigraphic developments.
The NCS has developed a user friendly website ncs.naturalsciences.be and hereby invites all geologists to consult the website, to contribute to the discussions wherever possible and to actively participate in subcommissions and working groups.
Brussels , February 2016
