Shown here is the famous cross-section from Lausanne, France, to the Po River Valley, in Italy, that was drawn by Emile Argand. From this figure one can see the huge overturned folds [nappes] and thrust sheets that sandwiched sedimentary deposits between two granitic massifs, the Aar Massif and the Insubrian zone. (The Insubrian zone is north of the Po River; it is named after the Insubres, who settled the area about 400 B.C.) By standard convention, cross-sections are usually exaggerated vertically by a factor of 10-20. It is also common to show with dotted lines the rocks that have been eroded since the folding took place, (Allègre, 1988).
