Forty Years of Thinking in Front of the Alps: Saussure's (1796) Unpublished Theory of the Earth

The four volumes of Voyages dans les Alpes.. published by Horace Bénédict de Saussure (1779-1796) consist of the description of seven trips, organized chronologically only in part. A large portion of Saussure's descriptions represents a composite assemblage of observations and interpretations, often not updated, borrowed from numerous itineraries, repeated many times during various years. The planned theory of the earth, mentioned repeatedly throughout the volumes, is replaced at the end by an Agenda or listing of observations to be made by his followers as a basis for this theory.

Circumstances and poor health prevented Saussure from writing his theory. Fortunately, all his personal papers have been preserved, and among them are carefully-dated field notes and short memos summarizing his ideas at a given time. These documents allow one to reconstruct the evolution of his geological thinking and to present what his unpublished theory, based mainly on the structure of the Alps, might have been.

Several phases in Saussure's thinking show his struggle to untangle himself from a pre-Wernerian to Wernerian heritage, and to break new ground dictated by his observations. These phases are discussed in chronological order under headings describing Saussure's new ideas.

Two versions (1786 and 1796) of the table of contents of Saussure's incomplete theory of the earth indicate the evolution of his synthesis toward a mature and almost modern outlook of planet earth.