The nature of the driving forces for plate tectonics has been a subject for intense, often heated debate, for more than a quarter of a century. On 15 April 1992 Peter Ziegler delivered the annual William Smith lecture to the Geological Society on the subject of Plate-Moving Mechanisms, followed by a series of lectures on related themes. This thematic set of papers, resulting from the meeting, covers some of the major issues discussed.
For more than a quarter of a century Earth Scientists have debated the nature of the forces which drive the lithospheric plates. One of the major problems has been whether mantle convection, including the activity of mantle plumes, dominates or whether boundary and plate forces, such as slab pull and ridge push, exert the most important controls on plate motions. Clearly the relative importance of the different forces involved may vary, both in space and time, and they may either reinforce or counterbalance each other depending upon the tectonic setting.
On 15 April 1992 Peter Ziegler delivered the annual William Smith Lecture to the Geological Society on the subject of Plate-Moving Mechanisms. This was followed by a further eight presentations on related themes by an international group geoscientists from Europe and North America. Of the nine papers presented at the meeting, six are included in this thematic set (Ziegler, Bott, Wilson, Searle et al., Doglioni, Pavoni). The other speakers were Randall M. Richardson, University of Arizona, Tuscon, USA, John F. Dewey, Oxford and Sierd Cloetingh, Free University,