Until a few decades ago, our understanding of the deep structure of Switzerland was relatively poor. Between 1985 and 1995 intensive investigations into the deep structure of Switzerland were carried out using geophysical methods (in particular near-vertical reflection seismology) as part of a Swiss National Research Project. In view of the new results, it seemed more appropriate to produce new, up-to-date profiles to a scale of 1:500 000 for the «Hydrological Atlas».
