The art of geological mapping in a precisely defined world: do only extreme environments pose a challenge for 2D geological mapping?

Geological map is mainly a result of the subjective interpretation of geological data collected as point (e.g. boreholes) and linear data (e.g. geophysical surveys), followed by their interpolation and extrapolation to areas where there is no data available. Currently, Geographic Information Systems (GIS) systems replace traditional cartographic methods that were widely used in the geosciences in the past. The unambiguous interpretation of analogue/paper geological maps is often a challenge, especially in those cases where the uncertainties and their extent were represented using artistic methods such as shading, hatching or using different symbols. 

In the past, the digitisation of geological maps involved the use of GIS software only as a graphical tool, resulting in a map developed for a paper publication. Such map was a redrawn version of a paper map, representing exactly the same vision as the author of the analogue map had. Today, GIS tools offer many spatial data processing functions that provide new information, which was not possible in case of paper maps. GIS analysis can be used to assess the quality of collected data, allowing geological data to be harmonised.
Today, to classify a digital map, geological data have to be structured at much deeper level than before The heterogeneity of geological data and the difficulty of acquiring it results in the necessity of introducing artificial boundaries on maps, especially when it comes to geological structures covered and/or deformed by overlying structures - such as the Carpathian substrate deformed and covered by the structures of the Alpine orogeny - These boundaries separate detailed structures from those that have not been identified. Some boundaries are entirely artificial and indicate the extent of possible interpretations rather than the extent of occurrence of geological structures. Similar problems arise with Quaternary substrates, which may have been subjected to strong stresses during glaciations, resulting in glaciotectonic deformations. Despite an apparently thoroughly investigated Quaternary cover, the discovery of glaciotectonic disturbances can still be a stroke of luck.