What is a geological map?
How are geological maps made?
The essential condition for establishing a geological detail map is a precise field survey, based on numerous measurements and observations. The topographic base is generally taken from maps at a scale of
1:10 000, such as those of the comprehensive cadastral plans.
In the case of a doubtful rock identification, complementary investigations are carried out in the laboratory on samples of these rocks.
At the end of the field survey, the geologist establishes an original draft at a scale of
1:25 000 and constructs some geological sections across the studied sector. He also writes an explanatory note that generally contains numerous illustrations.
The geological cartography section assures the direction of the project, carries out the editing of the map, establishes the final legend of the map and provides indispensable data for the cartographers.
Publishing geological information
Professional carographers carry out the cartographic work in close collaboration with the Swiss National Geological Survey.
The original geological map is scanned by the cartographic division. This document serves as a background for the manual digitisation of geological information on the screen.
The colours of the surfaces are decided during the editing phase. Between 12 and 16 base colours are used for any given sheet of the Geological Atlas, depending on the number of geological formations present.
The printing plates are then produced. The definitive colours are adjusted on the rotary press at the time of the printing of proofs and editions. About 1500 to 3000 copies of the maps are printed on robust paper.
Swiss Geological Survey Secretariat
Tel +41 31 963 25 68
Fax +41 31 963 25 45