Monday, August 31, 2009

Stratigraphic concepts and agetagging

Stratigraphic 'homonyms' are quite common, a result of ambiguous placenames which have been used to name stratigraphic units. The stratigraphic terms used in Jens' post on Table Mountain stratigraphy nicely illustrate this:
He wrote about the South African 'Peninsula Formation' which is a synonym for the 'Peninsula Sandstone'. Unfortunately, this 'Peninsula Formation' is homonym to the 'Peninsula Formation' from British Columbia. The latter is of Cretaceous age, whereas the South African was formed during the Ordovician!

Geoscientists using stratigraphic terms surely have a clear concept of what they mean. However, whereas for human readers it may be easy to determine such a concept by lithological descriptions or the broader geological or tectonic context, this is much harder for computer algorithms and thus, agetagging.
Fortunately, the regional context can easily be discovered by geotagging technologies, therefore the geographic concept of a stratigraphic term is most important. Stratigraphic homonyms may exist at much lower regional level, e.g. from different provinces or states and most likely there are also significant conceptual differences between scientists. etc etc. However, such regional concepts are sufficient for the approximation for our agetagging purposes. The concept of a South African 'Peninsula Formation' is surely completey different from the Canadian.

.. a lot of complications with 'strato-semantic' text analyis.. stratigraphic analysis of geoscientific texts requires a combined approach, good agetagging is not possible without geotagging.

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