The sight of undisturbed sedimentary rocks on the top of the Bolivian Andes in 2001 prompted this research into the magnitude of the unrelenting forces associated with plate tectonics.

My wife Betty who put up with my obsession with tectonics to the exclusion of all other domestic matters.

David J. Tompkins for valuable help with mathematical modelling.

Professor Richard Howarth, University College, London, for his help with the statistical analysis of the tensile stress forces.

Dr John Crocker for help with the verification of the mathematical analysis and encouragement.

Allan Wheeler, retired Government Scientist, for factual verification, constructive discussions & editing.

Dr Stuart Harker, Professor Emeritus, Heriot-Watt University, Edinburgh, for factual corrections and encouragement.

Dr Shigeyuki Suzuki, Professor Emeritus, Department of Earth Sciences, Okayama University for factual advice, editing, illustrations, and encouragement.

Dr Richard Moody, Professor Emeritus, Surrey University, Guildford, whose field trips inspired my love of geology.

The late Dr RF (Bob) Symes, Natural History Museum, who gave me a detailed insight into mineralogy.

Natalie Batten (BSc) for formatting and editing.

Viki Sizgoric for the original illustrations.

Jean Sippy and Ruth Weinberg for editing.

Brian Warshaw for collating the dates and correspondence associated with this project.

I also thank all my friends at the various Local Groups and affiliates of the Geologists’ Association and the Harrow and Hillingdon Geological Society for the encouragement they offered.