Hans Cloos was a prominent German structural geologist. He made pioneering studies of rock deformation, including granite tectonics.
Background
Cloos was born on November 8, 1885, in Magdeburg, Germany. His father, an architect, died young, leaving the upbringing of the three children to their mother, a highly gifted woman who contributed greatly to her son’s intellectual development.
Education
Upon completing his secondary studies at Saarbrücken and Cologne, Cloos began to study architecture at the Technische Hochschule in Aachen but soon became interested in geology. After a short period of study in Bonn and Jena he went to Freiburg im Breisgau, where he received his doctorate under Wilhelm Deecke.
Between 1909 and 1913 Cloos worked in applied geology in South West Africa and Java. In 1914 he qualified as a lecturer at the University of Marburg, and in 1919 he was appointed professor of geology and paleontology at the University of Breslau (now Wroclaw, Poland). He was called to the University of Bonn in 1926 to succeed Gustav Steinmann.
In his dissertation, in which he examined the tectonic relationships between the folded mountains and plateaus of the Jura south of Basel, Cloos treated subjects that appeared in his later work: tectonics, structural geology, and internal dynamics. His stay in South West Africa presented Cloos with problems involving the mechanics of magmatic intrusion when he investigated the granite massifs in the Erongo Mountains. As a petroleum geologist in Java, he was able to study active volcanoes and their structure.
During his years in Breslau, Cloos developed the field that became known as granite tectonics, the reconstruction of the dynamics of emplacement of a mobilized pluton from its internal structure (1921, 1922, 1925). Its basis was provided by the great granite massifs of Silesia. Cloos discovered that the granite, considered until then as massive and essentially structureless, bears clearly oriented features gained during or directly after its intrusion. He applied granite tectonics to the Bavarian forest near Passau, and in Norway and North America (1928). The results obtained during the years at Breslau are among his most significant achievements.
At the same time that Cloos developed granite and magmatic tectonics, still another procedure for investigating similar problems was discovered by Bruno Sander - structural petrology, which examines, among other things, adjustment and behavior of mineral granules in a solidifying, magmatic liquid solution under tectonic influence. For a time there was sharp opposition between the two lines of inquiry. This resulted in scientific polemics between Cloos and Sander, which are now settled.
When Cloos moved from Breslau to Bonn in 1926, he turned his attention to other tectonic problems: jointing and cleavage as typical of the deformation of solid rocks, especially in the Paleozoic formations of the Rheinische Schlefergebirge (the area around Bonn) folded and faulted in the Hercynian orogeny, as well as the reproduction of tectonic phenomena and processes in the laboratory. He may have been the first to make extensive use of wet clay. His experiments on rift valley formation using wet clay (1931) have found a place in the literature and are particularly impressive, Many trips, including those to Africa and North America, widened his knowledge and experience and enlarged his view. The results can be seen in his outstanding textbook on internal dynamics (1936). Moreover, the years in Bonn witnessed more new knowledge: the division of the old continental masses into polygonal fields, the existence of Grundschollen (ground blocks) and Erdnähten (geofractures) which put Cloos in opposition to Alfred Wegener (1947) - the significance of the buckling processes in the earth’s outer crust, the mechanics of volcanic processes in the so-called” embryonic volcanoes” in Württemberg (1939), and many lesser studies on the mechanics of folding and faulting.
Cloos always placed tectonic considerations foremost, regarding the earth’s crust as an architectonic edifice. In his view the significance of the structural form and its analysis were primary: the investigation of the historical development of the mechanical processes that led to this structural form were of lesser interest.
Membership
Academy of Sciences of Berlin
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Germany
Academy of Sciences of Göttingen
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Germany
Geological society of Germany
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Germany
Geological society of Finland
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Finland
Geological society of London
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United Kingdom
Geological society of Sweden
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Sweden
Geological society of the United States
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United States
Geological society of Peru
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Peru
Natural Science Society of Schaffhausen
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Switzerland
Personality
In many respects, Cloos had an artistic temperament, filled with passion and enthusiasm for his science; and he knew how to convey this feeling to his students. His popular book Gespräch mit der Erde (1951) is a further expression of this ability.
Connections
Cloos married Elli Grüters, the daughter of an orchestra conductor, who bore him four children.