Repatriated in 1936 during the Spanish Civil War, he soon revealed his interest for research and exploration, instilled by Jules Verne's novels, while Jean-Henri Fabre's Souvenirs entomologiques led him to observe and collect insects.

He recalls it was in August 1945, during a stay at the "École de haute montagne" (Mountaineering School) in Chamonix, that he first cut steps in the ice of the Bossons Glacier and he realized he was ″climbing on water″.

[1] He soon contacted the Club alpin français which was at that time preparing an expedition to Fitz Roy (3,405 metres (11,171 ft)), a still unconquered Argentine summit in the Patagonian Andes.

While staying at the base camp, he made a new topographic survey of the surrounding area, then poorly mapped on Argentine documents which showed very approximate elevations.

He climbed twice to Camp III, 400 metres (1,300 ft) below the summit, which was reached by Lionel Terray and Guido Magnone in February 1952 after more than a month's approach and waiting.

In March 1952, about 4,700 metres (15,400 ft) above sea level in Nevado Juncal close to Aconcagua, he first observed snow penitents, mysterious structures already encountered by Charles Darwin and attributed by natives to carving of névé by strong winds.

In the following decades, his expertise in glaciology and geophysics will be called upon several times in Latin America, notably by the Peruvian government and UNESCO, before and after the Yungay disaster (a debris flow caused by the outburst of lakes near the Huascarán Glacier, making 20,000 casualties on 31 May 1970).

[8] In Grenoble, he set up in 1959 at the master level a new syllabus in general geophysics which will flourish in the 1960s when the Earth's sciences will be refounded by the plate tectonics "theory".

Two articles[9][10] published in 1969 and 1970 on the modelling of convection within the Earth's mantle showed him, with Claude Allègre, Xavier Le Pichon and Dan McKenzie, in the very closed circle of European scientists at the leading edge of the new theory.

He also modelled the postglacial rebound of the lithosphere as observed in Fennoscandia or Canada following the disappearance of Quaternary ice caps, which allowed him to infer the mechanical properties of the Earth's mantle, its rheology and its viscosity.