(b. Lyons, France, 3 July 1859; d. Grenoble, France, 23 October 1930)
metamorphic petrology, structural geology, geotectonics.
Termier’s grandiose synthesis of the geological structure of the Alps (1930) made him the founder of modern tectonics and geodynamics. His works are numerous and stylistically unsurpassed. His vivid essays and biographies of his great teachers are collected in À la gloire de la terre, La joie de connaître, and La vocation de savant; a fourth volume, Mélanges, was published posthumously by his daughter, Jeanne Boussac-Termier.
Termier’s interest in literature developed at an early age. His father, Francisque Termier, was often away from the family home in Lyons, and his mother, Jeanne, guided him through his early years. Termier proudly recalled having read poems to his mother at the age of five. A brother, Joseph, was born when Pierre was thirteen.
In 1868 Termier was sent to the Collège des Maristes in Saint-Chamond (Loire), where he developed a passion for mathematics, in addition to his favorite subjects, literature and philosophy. After graduating in 1876 he continued his education in Paris at the École Sainte-Geneviève and, from 1878 to 1880, at the École Polytechnique. On a mountaineering trip to the Belledonne Massif in the western Alps, Termier discovered his vocation for geology. In 1880 he entered the École des Mines in Paris, where he attended the mineralogy course of Ernest Mallard. His thesis was based on a field study of igneous rocks in the Harz Mountains.
In 1883 he married Alice Beylier, and they made their first home in Nice, where Termier was appointed inspector of mines (ingénieur ordinaire). Administrative duties took him as far as Corsica. But since he preferred teaching, he applied for the vacant chair at the École des Mines in Saint-Étienne. In 1885 Termier was appointed professor of physics and electricity and later of mineralogy and geology. Under the auspices of the Service de la Carte Géologique de la France he began geologic mapping of the Massif Central (Plateau Central). Although he was attracted by the Tertiary volcanoes of Mont-Mézenc, his work soon focused on the metamorphic Paleozoic basement in the area of Saint-Étienne, especially Mont-Pilat. Termier was greatly stimulated by his colleague Urbain Le Verrier, professor of metallurgy and chemistry, who had also become involved in geologic mapping through his close friendship with August Michel-Lévy, director of the geological survey. Le Verrier concentrated on the problem of granite formation, particularly the process of feldspathization. Termier’s field research on the Massif Central was incorporated in five sheets of the Carte géologique détaillée de la France (1:80,000).
For thirty years Charles Lory had been the only geologist to carry out field mapping in the French Alps. It was only after Lory’s death in 1888 that Marcel-Alexandre Bertrand, who had introduced the nappe theory into Alpine geology, transferred his field research from the Provençal thrust belt to the Alps. For this project, Bertrand assembled a team of geologists. Lory’s successor at the University of Grenoble, Wilfrid Kilian, was entrusted with the mapping of the High Calcareous Alps of Savoy. Just at this time the Termier brothers, who were climbing their favorite mountains in the Haute Vanoise, suffered an accident. Receiving word of this and intrigued by Pierre Termier’s reputation, Bertrand recognized in him the ideal collaborator for the work in the massifs and the metamorphic zone of Savoy. An extremely fruitful cooperation began, and Termier soon regarded Bertrand as his great mentor and friend. Together they explored the Vanoise in the summer of 1890. Termier went on to complete the mapping of the Haute Vanoise for the 1:80,000 map series. His initial report of 1891 was an epoch-making contribution to Alpine geology, since for the first time the progressive stages of the regional metamorphism were mapped over a considerable distance. The metamorphic grade, transgressive across the stratigraphic sequence, was found to be controlled by the Alpine structure alone. This discovery, in turn, confirmed Lory’s early assumption that the axial belt of crystalline schists (schistes lustrés) represented a transformed Mesozoic sedimentary sequence. In his report of 1894 on the Grandes Rousses Massif, Termier was able to distinguish also between Hercynian and superimposed Alpine fold structures.
In 1894 Ernest Mallard died suddenly, and Termier was appointed to succeed him as professor of mineralogy and petrology at the École des Mines in Paris. With some regret the Termiers, with their son and five daughters, left the countryside of southern France for Paris, where a second son was born. They maintained a second home at Varces-Allières-et-Risset, near Grenoble. Although the ensuing years brought further triumphs to Termier’s successful career, he was spared neither grief nor sorrow. It soon became apparent that his wife suffered from parkinsonism. In 1906 his elder son died in an accident at the age of thirteen, and the following year Bertrand died. Termier found some comfort in a new friendship with the writer Léon Bloy.
After the death of Auguste Michel-Lévy in 1911. Termier was elected director of the Service de la Carte Géologique de la France. The following year his teaching responsibility was increased to include the main course in physical geology at the École des Mines in Paris. Termier attracted many students, for no one could speak of the beauty of the mountains with greater skill and affection. He stressed also his belief in the philosophic and religious values of science, looking upon faith and science as coming from the same source.
In 1914 Termier was elected inspector general of mines. During World War I he served as colonel with the French artillery. In 1916 his wife died in Varces-Allières-et-Risset. Shortly afterward, his son-in-law Jean Boussac died from an injury received near Verdun; Boussac was noted for his works on the Eocene Alpine flysch. Termier suffered yet another bereavement with the death of his younger son from meningitis in 1924.
In 1909 Termier was elected member of the Académie des Sciences. He was made an officer of the Legion of Honor in 1914 and a commander in 1927. He had three terms as president respectively of the Société Minéralogique and the Société Géologique of France, and was vice-president of the Académie des Sciences; at the time of his death. Termier was president elect of the Academy. The Geological Society of London elected him foreign correspondent in 1923 and foreign member in 1929. At the centennial of the Geological Society of France in 1930, he received the degree of doctor honoris causa from the University of Innsbruck.
Termier’s love of travel enabled him to make the expeditions necessary to unravel the tectonics of Alpine Europe. Research and consulting work took him to Scandinavia, the Urals, Siberia, Mexico, the Colorado Plateau, the Canadian Rockies, and Quebec, as well as to North Africa and Spain. In 1930, on his last trip to Morocco, he fell ill and died shortly after his return to Grenoble.
Termier’s field research was apparently directed toward the metamorphic rather than the structural history of the areas he had selected for study. In the Franco-Italian Alps he searched for the causes of regional metamorphism. At first he tried to organize his results so that they would fit into the framework of the widely accepted theory of dynamic metamorphism, in which heat was attributed to the mechanical energy produced during folding and thrusting. By 1903, however, Termier had become a bitter opponent of the theory. Dynamic action deformed but did not transform, and mylonitic rocks were its only product, he argued at the Ninth International Geological Congress in Vienna (1903). He saw the cause of regional metamorphism related, somehow, to the depth of burial in the geosyncline. But geologic depth alone would not be sufficient to cause metamorphism. He assumed the causative factor to be the influx of juvenile liquids and vapors, the colonnes filtrantes, which brought with them alkali silicates. Extending the ideas of Le Verrier, he compared the process of feldspathization with the spreading of a grease spot (the tâche d’huile mechanism). Termier concluded that the progressive stages of regional metamorphism would ultimately result in massive granitic rocks. The negligible role that he attributed to penetrative movements was subsequently challenged, mainly by the Austrian school, which initiated the study of petrofabrics in support of its case.
Termier’s contributions to regional tectonics effected revolutionary changes in the perception of global dynamics, at first only among Alpine geologists. In the dramatic dispute on the structure of the eastern Alps, Termier, as Bertrand’s disciple, emerged as the new leader of the French structural geologists, all of whom adhered to the concepts of Eduard Suess as set forth in his Das Antlitz der Erde. Suess elucidated for the first time the global grouping of mountain belts in space and time. He argued that the structure of the Alpine-Carpathian mountains could best be explained as the product of a one-sided tectonic drive that thrust the sedimentary fill of the Tethys sea onto the old European Vorland. Termier first visited Suess late in 1899 for advice concerning French explorative drillings in the Carpathians. The results confirmed Suess’s prediction that the Upper Silesian coalfield would extend southward beneath the Carpathian thrust sheets. The French were the first to translate Suess’s classic; their elaborate edition (1897–1918) appropriately opens with a preface by Bertrand and concludes with a eulogy by Termier.
Large-scale nappe structures (Bertrand’s nappes de recouvrement) had been incontestably demonstrated in the Swiss Alps by Hans Schardt (1893) and Maurice Lugeon (1902), and in the Franco-Italian Alps mainly by Termier himself (1899, 1902). It was the metamorphic petrology of the Vanoise that enabled Termier to decipher the tectonics of that region. The key to the structure of the Briançonnais zone in particular was seen in the interpretation of the “thrust slice number four” (quatrième écaille); thus the crystalline capping of a few mountaintops west of Briançon became also the cradle of a tectonic principle: that of the “squashing thrust plate” (the traîneau écraseur). A rigid mass of schists had been shoved westward over folded flysch and older sediments, which built up the fanlike structure of the Briançonnais. The fold crests of the overridden fan were thrown into tucks and flattened out under the advancing plate. In general, nappe structures were formed either by recumbent folding, gravity sliding, or overthrusting. The traçneau écraseur, however, is a thrust plate actively pushed over the top of another block; its width is a measure of the shortening of the crust.
Although the nappe interpretation of the Swiss Alps necessitated corresponding structures in Austria, the constitution of the eastern Alps, some 500 kilometers in length, still remained obscure until, after the International Geological Congress in Vienna (1903), Friedrich Becke led a field trip to Ziller Valley and the Hohe Tauern. On the summit of Amtshorspitze, Termier boldly declared the eastern Alps to be a pile of nappes and the Hohe Tauern in particular to be a window exposing the geosynclinal fill of schistes lustrés; he could not help seeing lithological and structural similarities to the western Alps, including the traîneau ècraseur, which here assumed much larger dimensions. Shortly afterward Termier proved his claim by verifying the window structure of the Hohe Tauern as well as the Lower Engadine in Switzerland. The Hohe Tauern window implied a thrust plate, 120 kilometers in width, similar in size to overthrusts that had already been inferred in Scandinavia. To Termier, the entire structure of the Alps seemed to require a total crustal shortening of 500 kilometers or more. He himself did not fail to consider the geotectonic aspects of this conclusion, and although he did not accept Alfred Wegener’s notion of continental drift, he insisted that considerable lateral motion of the crustal blocks had occurred.
Termier’s classic perception of the structure of the Alps underwent much modification, but its basic implication of large-scale plate motion was reaffirmed in the later works of Émile Argand, Rudolf Staub, Leopold Kober, and others.
I. Original Works. Among Termier’s publications are: “Étude sur le massif cristallin du Mont-Pilat, sur la bordure orientale du Plateau Central entre Vienne et Saint-Vallier . . . ,” in Bulletin des Services de la carte géologique de France et des topographics souterraines, no. 1, I (1889), 1–58; “Étude sur la constitution géologique du massif de la Vanoise (Alpes de Savoie),” ibid., no. 20, II (1891), 367–514; “Le massif des Grandes-Rousses (Dauphiné et Savoie),” ibid., no. 40, VI (1894), 169–288; “Les nappes de recouvrement du Briançonnais,” in Bulletin de la Société géologique de France, 3rd ser. , 27 (1899), 47–84; “Quatre coupes à travers les Alpes franeo-italiennes,” ibid., 4th ser., 2 (1902), 411–433; “Les schistes cristallins des Alpes occidentales,” in International Geological Congress, comptes-rendus 9th, Vienna, 1903 (Vienna, 1904), 571–586, repr. in La joie de connaître, suite de À la gloire de la terre (Paris, 1926); “Les montagnes entre BrianÇon et Vallouise,” in Mémoires pour servir à l’explication de la Carte géologique détaillée de la France (Paris, 1903); “Sur la structure des Hohe Tauern (Alpes du Tyrol),” in Comptes rendus hebdomadaires des séances de l’Académie des sciences, 137 (1903), 875–876; “Les nappes des Alpes orientales et la synthèse des Alpes,” in Bulletin de la Société géologique de France, 4th ser., 3 (1903), 712–765; “Sur la fenêtre de la Basse-Engadine,” in Comptes rendus hebdomadaires des séances de l’Académie des sciences,139 (1904), 648–650; “Roches à lawsonite et à glaucophane et roches à riébeckite de Saint-Véran (Hautes-Alpes),” in Bulletin de la Société française de minéralogie, 27 (1904), 265–269; “Les alpes entre le Brenner et la Valteline,” in Bulletin de la Société géologique de France, 4th ser., 5 (1905), 209–289; La synthése géologique de Alpes (Liége, 1906), repr. in À la gloire de la terre, souvenirs d’un géologue (Paris, 1922); “Sur la genèse des terrains cristallophylliens,” in International Geological Congress, comptes rendus 11th, Stockholm, 1910 (Stock holm, 1912), I, 587–595; “Les problèmes de la géologie tectonique dans la Méditerranée occidentale,” in Revue générale des sciences,22 (1911), 225–134, repr, in À la gloire de la terre . . . ; “La dérive des continents,” Bulletin de l’Institut océanographique de Monaco, no. 443 (15 Apr. 1924), repr. in La joie de connaître . . ., translated as “The Drifting of the Continents,” in Smithsonian Report for 1924 (1925), 219–236; La vocation de savant, suite de À la gloire de la terre et de La joie de connaître (Paris, 1929); Mélanges, pref, by Jeanne Boussac-Termier (Paris, 1932).
II. Secondary Literature. The most complete biographies are A. George, Pierre Termier (Paris, 1933), and E. Raguin’s éloge in Bulletin de la Société géologique de France, 5th ser., 1 (1931), 429–495, including a complete bibliography. Other notices are by L. Lecornu, in Comptes rendus hebdomadaires des séances de l’Académie des sciences,191 (1930), 685–687; G. Aichino, in Bollettino, R. Ufficio geologico d’Italia,55, no. 12 (1930), 1–4; E. J. Garwood, in Proceedings of the Geological Society of London,87 (1930–1931), 1x–1xii; L. J. Spencer. in Mineralogical Magazine,23 (1933), 359–360; and the pref. by Jeanne Boussac-Termier in Mélanges (Paris, 1932).
E. B. Bailey, in Tectonic Essays, Mainly Alpine (Oxford, 1935), sets Termier’s structural synthesis of the Alps in historical perspective; and H. H. Read evaluates his contribution to metamorphic petrology in The Granite Controversy (London, 1957).