Experimental tectonics: from Sir James Hall to the present

The subject of experimental tectonics is the study of geodynamic processes by means of laboratory scale models. The first roughly scaled experiments w ere performed by Sir James Hall about two centuries ago, in the intellectua l atmosphere generated by the appearance of Hutton's Theory of the Earth (H utton, J., 1795. Theory of the Earth, with Proofs and Illustrations, Vols. I & II. Cadell & Davies, Edinburgh). Their aim was to test the hypothesis t hat the folding of originally horizontal strata is the result of lateral co mpression. The idea to test hypotheses by laboratory experiments had alread y been applied by Hall to petrological problems (crystallization and meltin g) not involving scaling. Interestingly, however, he constructed a scale mo del of a Gothic cathedral, using a line of reasoning parallel to that used in his tectonic experiments. From these beginnings, the theory and practice of scale models have grown to become an important part of an integrated ap proach to the study of geodynamics. One topic which is at present the focus of much attention is the choice of model materials correctly scaling the t emperature dependence of lithospheric materials. As an example, a brief dis cussion is offered of two geodynamic problems where the application of scal e models is proving very fruitful: the initiation and time-history of subdu ction of oceanic and continental lithosphere., and the tectonic evolution o f orogenic wedges. (C) 2001 Elsevier Science Ltd. All rights reserved.