Core values: the first Hans-Cloos lecture John Knill Abstract The traditional scope of engineering couvrant d’autres domaines relatifs aux travaux de geology was the application of geology in l’inge´nieur, a` l’environnement et aux risques naturels. construction practice, but this has become widened La discipline se situe a` l’interface entre l’observation in time to embrace other fields of engineering, et la description de processus naturels relevant des environmental concerns and geological hazards. The sciences de la Terre et l’e´tude des proprie´te´s des subject lies at the interface between the observation mate´riaux et la maıˆtrise de la mode´lisation ne´cessaires and description of natural processes associated with au dimensionnement et la mise en œuvre d’ouvrages the science of geology and the knowledge of relevant de l’art de l’inge´nieur. Une conse´quence de numeracy and material properties required for cette situation est que la ge´ologie de l’inge´nieur a e´te´ design and manufacturing central to the perc¸ue comme secondaire par rapport a` la me´canique engineering process. A consequence is that des sols et la me´canique des roches au sein de la engineering geology has come to be seen as ge´otechnique, bien que la contribution de cette dis- secondary to soil and rock mechanics within cipline soit ne´cessaire tout au long du processus de geotechnical engineering, even though the subject construction, les de´passements de couˆts, les retards et is required to be applied throughout the accidents pendant la construction e´tant commune´- construction sequence and cost over-run, delay ment attribue´sa` des difficulte´sge´ologiques. Le roˆle de and failure during construction are commonly la ge´ologie de l’inge´nieur comme discipline doit eˆtre ascribed to geological errors. The role of de´fini et le roˆle central de la ge´ologie doit eˆtre a` nou- engineering geology as a discipline needs to be veau souligne´ en ame´liorant notre compre´hension des defined and the central role of geology has to be incertitudes d’origine ge´ologique dans la constitution re-emphasised by improving the understanding of du risque ge´otechnique, en de´veloppant des proce´- geological uncertainty in contributing to dures performantes pour la de´finition de mode`les geotechnical risk, developing improved protocols ge´ologiques re´alistes et en e´tablissant des me´thodes in the formulation of meaningful geological and syste´matiques pour la pre´sentation des rapports ground models, and more systematic methods of ge´ologiques. Les associations nationales et interna- presentation of ground-related reporting. National tionales de ge´ologie de l’inge´nieur ont un important and international organisations in engineering de´fia` relever en indiquant la direction a` suivre pour geology have an important challenge in providing que le roˆle et le statut de la discipline soient mieux the leadership through which an enhanced function reconnus. and status for the subject can be attained. Keywords Hans Cloos Æ Core values Æ Engineering Re´sume´ Le champ traditionnel de la ge´ologie de geology l’inge´nieur a e´te´ l’application de la ge´ologie a` l’art de construire, mais ce champ s’est e´largi avec le temps, Mots cle´s Hans Cloos Æ Valeurs fondamen- tales Æ Ge´ologie de l’inge´nieur It is with great regret that we record John Knill’s death on 31 December 2002. Tribute to Hans Cloos Received: 9 October 2002 / Accepted: 10 October 2002 Published online: 21 February 2003 Hans Cloos was one of the main contributors to the de- ª Springer-Verlag 2003 velopment of modern structural geology during the first DOI 10.1007/s10064-002-0187-9 Bull Eng Geol Environ (2003) 62:1–34 1 J. Knill half of the twentieth century. Despite his writings being killed in Turkey and in view of the quality of some guest almost exclusively in the German language his thinking lectures Cloos had been invited to give it was not had an enormous influence at the time; it forms the basis surprising that in 1919 he was appointed to the chair of of much modern structural geology and his work is still geology when only thirty four. quoted. The economic difficulties in post-war Germany restricted Cloos was born on 8 November 1886 in Magdeburg in opportunities for fieldwork so Cloos concentrated his ac- Germany and he gained his geological training at the tivities in the granite quarries of Stehlen, 30 km south of University of Freiburg im Breisgau which is located near Breslau. He was able to map in detail the relationships the juncture of the Alps and the Black Forest [much of between joint orientation, mineral alignment and dykes this section draws upon Balk (1953)]. His PhD thesis was associated with the intrusion and post-intrusion history. concerned with the mechanism of disturbance of the This experience married well with his earlier observations Jurassic cover rocks which form the Jura mountain chain. in the Erongo Mountains where he had observed the role He then travelled to south-west Africa at the invitation of of wall-rock fracturing in controlling stoping at the granite his uncle where he mapped in the Erongo Mountains. contact and thus the intrusion of the igneous mass. In 1927 This visit is described in graphic, almost poetic, language he carried out preliminary studies of the Sierra Nevada in his book ‘‘Conversation with the Earth’’ (Cloos 1954), batholith in the USA which formed a perceptive and ac- originally published in German in 1947. The book vividly curate framework to subsequent more detailed studies by describes episodes in his professional career which is others, including his brother Ernst Cloos. His major con- seen as a voyage of both personal and scientific discov- tribution to the understanding of granite tectonics is re- ery. The opening chapters, on his African experience, flected by his name being incorporated in the sub-title to illustrate features of his working style which character- Robert Balk’s monograph on the ‘‘Structural Behaviour of ised the remainder of his career. In particular he is seen Igneous Rocks’’ (Balk 1948). to be a careful field observer who was able to prepare During a student field trip to the Harz Mountains he had detailed, precise field sketches of structures and litho- been able to observe the north-eastern margin where logical relationships on all scales. However, most im- Palaeozoic rocks have been thrust over a younger suc- pressive are his superb three-dimensional interpretations cession. He recognised the manner in which large-scale of regional geological structures and topographical structural deformation leaves a fingerprint in the form of landforms which he continued to draw throughout his small-scale structures, thereby indicating the direction and life. Some of his drawings were reproduced by Richard style of tectonic translation. Wolters, a former student of Cloos and a Hans-Cloos In 1925 Cloos became head of the Department at the Medallist (Wolters 1976), to mark the 25th anniversary of University of Bonn where he spent the remainder of his Cloos’ death. career. He was able to follow up his interests in small-scale Almost immediately on his return from Africa he signed tectonic structures in the west German Devonian and a contract to travel to Indonesia to work as an explo- Carboniferous slates, amongst other areas, where he and ration oil geologist for 2 years. This decision caused him colleagues addressed issues such as the relationship be- some torment because he felt that ‘‘I had sold something tween folding and slaty cleavage, relative ages of quartz much more valuable and irretrievable—two long years of veins, variations in fold trend and the role of underlying my young life and of my capacity for work’’ (Cloos 1954) basement rocks on the deformation of the cover. He However, he recognised that he needed financial capital published many papers on these subjects which under- to fulfil his ambition to establish himself in an academic pinned a major concentration of his research effort in career. Fifty years later, my own Professor told me, in all Germany and other countries for the rest of his life. seriousness, that I was ‘‘selling my soul to the devil’’ Many individuals, almost unknowingly, will be familiar when I advised him that I was to pursue a career in with one aspect of his research and this relates to the engineering geology. Nearly 50 years farther on it is re- laboratory experiments in which large blocks of clay were grettable that such arcane views are still firmly fixed in progressively extended under tension. Textbooks on academic minds. Nevertheless, the relevant chapters in structural geology commonly contain reproductions of ‘‘Conversations with the Earth’’ indicate that his period photographs of the model graben formed in this way. He in Indonesia was by no means intellectually sterile, no- had recognised, from field observations, that the direction tably in relation to the appreciation he gained of modern of the imposed stress influenced the resulting fracture volcanoes. Like most field geologists he became frus- system and that clay provided a suitable, scaled medium trated by days of exploration in the jungle searching for by which to model rock mass behaviour. Using these rare exposures, and never appeared to return to such dramatic experiments he was able to confirm field inter- terrain. pretations of the relationship between stress, deformation On his return to Germany he began lecturing at the Uni- and fracture formation. Direct field observations made versity of Marburg, but this was overtaken by service in within the Rhine graben confirmed that the styles of the First World War from which he was released on faulting seen in the model were actually present.