Measurement, portrayal and analysis of orientation data and the origins ofearly modern structural geology (1670-1967)

Dip and strike measurements were made by miners as early as 1505 and by the 1770s took place in a 'geognostical' context. Early portrayal of dip and s trike in maps and the emergence of cross-sections and block-diagrams is dis cussed. In the 1820s, recordings of cleavage and foliation, lineation, join ts, faults and slickensides began. By the 1840s interest in Elie de Beaumon t's Systemes de Montagnes encouraged graphical summaries of two-dimensional orientation data (e.g. the strike of bedding, mineral veins or joints). To wards the close of the nineteenth century, primary effort was devoted to re gional mapping, resulting in improved understanding of the nature of struct ures, particularly 'Alpine' thrust tectonics. The emergence of Hans Cloos' school of 'granite tectonics' in Germany in the 1920s, and its subsequent u ptake in the United States, with the emigration of Robert Ball; and Ernst C loos in 1923 and 1930, is noted. Meanwhile, in Austria, Waiter Schmidt and Bruno Sander were developing 'structural petrology, dominated by the micros copic analysis of grain-orientation. Its enthusiastic take-up in Europe, Sc andinavia and the USA popularized statistical analysis of three-dimensional orientation data. As scepticism grew regarding kinematic interpretations m ade by structural petrologists, interest in structural analysis based on fi eld mapping returned in the 1940s. The subsequent emergence of early 'moder n' structural geology in Britain, with its emphasis on statistical analysis of small-scale structures, is discussed. The turning point is placed at ab out 1952.