Wednesday, July 30, 2014

Classification of igneous rocks revisited

Petrology, I must admit, was never my favourite subject even though I had to do quite a bit of it during my time as a student. Even my Honours project had a petrological component. An important tool for the classification of igneous rocks is the QAPF diagram which forms the basis of the IUGS classification of igneous rocks (Le Bas and Streckeisen, 1991). It was interesting to go back to this original publication to read about the considerations that led to the adoption of the classification schema. The general principles are solid science. In some of the finer points, however, it becomes apparent that this classification schema comes from the pre-digital age.

"One of the merits of the TAS system is that the boundaries are definitive although they could be criticized as over simplistic. Definitive boundaries remove the ambiguity in naming a rock which plots near a boundary between two adjacent rock types. The simple boundaries of the TAS system also enable the classification to be constructed in a few minutes by pencil and ruler"
Furthermore, the TAS classification system only takes into account the sum of Na2O + K2O over SiO2 and does not account for any other major elements even though such classification systems had already been proposed (e.g. De La Roche et al. 1980).
"[It] was not adopted, partly because the two cation per mil parameters were difficult to calculate without electronic assistance"
Certainly, in the age before widespread use of spreadsheet calculation software, this might have been an argument. A bit more difficult to follow is the following argument:
"The most common interpretations made by geologists are petrogenetical, but there could also be aesthetic considerations."
Robert Huber, Jess Robertson and myself (JK) have started to look more closely at the classification of igneous rocks in the dawning age of data intensive research in the geosciences. Watch this blog for more on this subject.


Thank you to Jess Robertson for pointing out this gem.


De la Roche, H., J. Leterrier, P. Grandclaude, and M. Marchal (1980), A classification of volcanic and plutonic rocks using R1R2-diagram and major-element analyses — Its relationships with current nomenclature, Chemical Geology, 29(1–4), 183–210, doi:10.1016/0009-2541(80)90020-0.

Le Bas, M. J., and A. L. Streckeisen (1991), The IUGS systematics of igneous rocks, J Geol Soc, 148(5), 825–833, doi:10.1144/gsjgs.148.5.0825. Online also available at

Monday, July 14, 2014

Australia Through Time - iPad App

On the weekend 11-13 July 2014 various Australian government institutions had invited to join GovHack 2014.

Governments collect and publish enormous amounts of data, but have limited resources to get it into the hands of their citizens in engaging ways. GovHack is an event to draw together people from government, industry, academia and of course, the general public to mashup, reuse, and remix government data. GovHack is about finding new ways to do great things and encouraging open government and open data.

Most projects targeted the obvious data, like census data or the national archives. Science data are not that attractive because the sources are normally not accessible through simple API and often domain knowledge is needed to understand the data. Not all entries have to be applications in the sense of an app, also interactive infographics are welcome. One entry this year made use of data from Geoscience Australia to make an interactive infographic of the development of the Australian continent through time.

The Australia Through Time iPad App is an interactive app that runs on iPad or in the browser, showing the geological, mineral and biological history of Australia from the Cambrian to the present. It is based on the Australia Through Time poster by Geoscience Australia.This app presents the data in a visually appealing format, condensing it into smaller, readable screens and includes an animated sea-level bar and continental-drift visualization which makes changes in the data more apparent. It uses an intuitive drag gesture to slide through the timeline and display varying content.

Tuesday, April 15, 2014

Webinars "iDigBio and Using and microdata for data discovery" 2014-04-15 at 1600 EDT

The topics for the next C4P Webinar are iDigBio (Gil Nelson, Florida State University) and Using and microdata for data discovery (Douglas Fils, Ocean Leadership Consortium).

The link to the webinar is
WebEx link for April 15, 4-5p ET (the date stated at the link updates weekly)
If a password is required, enter the Meeting Password: 73131647

For plain text postings where the link did not show up: Any updated links or information as well as the updated webinar schedule and archived presentations will be posted at

iDigBio (Gil Nelson, Florida State University)

Integrated Digitized Biocollections (iDigBio) is NSF's national resource for facilitating and enabling the digitization of biological and paleobiological collection objects in non-federal, U.S. biodiversity collections. Through its portal it makes available data and images for millions of biological specimens in electronic format for the research community, government agencies, students, educators, and the general public.

Using and microdata for data discovery (Douglas Fils, Consortium for Ocean Leadership)

HTML5 developments in the area of microdata have provided methods for resource discovery based on structured data embedded into HTML pages.  Combined with the Dataset and other vocabularies this facilitates a means to bring structured data about scientific data resources to web pages.  This talk will demonstrate examples of these patterns applied to and other sites.  It will further provide live examples of these patterns and discuss methods that could be used to enhance domain specific data offerings.  

The format is 20 minutes per presenter, with two main parts: (a) a show-and-tell presentation of the science and the resource (b) discussion of the key informatics needs that the resource is facing. The intended audience for this webinar is professional paleogeoscientists and cyber/computer scientists.  All webinars will be recorded and publicly archived at

More about C4P:
Technical information for webinars: