The authors present the following hypothesis: The External Massifs of the Alps are formed by units which can be followed from massif to massif. Namely, two very well differenciated series (a serie with pinite and another one with metamorphosed conglomerates) can be detected over a very long distance. The stratigraphy, the petrology, the field relationships and the isotopic ages of these series are discussed. The authors tentatively compare these series to those of the French Massif Central and the Penninic Alps.