Mapping and modelling of granite cavities: Problems in the representation of forms and work scale


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August 2008


The granite forms existing in Galicia are classified in three groups by their dimensions: mega-forms or large forms, mesoforms or intermediate forms, and microforms or minor forms. Megaforms are those whose minimum dimensions are around 100 m though may usually have kilometric dimensions. Mesoforms or intermediate forms are located between hundreds and dozens of meters. Finally, microforms or minor forms are those that measure less than 10 m though in extreme cases may reach the inferior limit assigned to mesoforms. Granite caves are associations of these three types of microforms. In spite of their dimensio-nal differences, the 3 types of forms have great importance in the interpretation of the genesis and evolution of the cavities. In the graphic representation of granite caves there are generally used the scales 1:50 or 1:100 with equidistances of half meter. Therefore, the minor forms only appear referenced in the cartography indicating the place where they are located. Symbols are classified in many different morphogenetic groups using as reference the same proposed in the Geomorphological Map Guide of IGME where there exist symbols to represent granitic mega-forms (e.g., inselbergs, fractures or faults) but not the necessary ones to represent mesoforms and microforms, and even less for the subterranean domain normally ignored or underestima-ted up to now. An additional problem is that in pseudokarstic domains there co-exist two types of forms of endogenous (for example, exfoliation surfaces) and exogenous (for example, pot-hole) origins. In order to solve these problems, it was decided to employ the same symbology that is used with other type of rocks (e.g., limestone) though with a specific colour for the forms developed on plutonic rocks of endogenous or exogenous origins. The used symbols...


Galicia, Limestone, Mesoforms

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Cuadernos Laboratoiro Xeoloxico de Laxe, Vol. 33, no. 33 (2008-08-01).