The rate of change of the size and shape of a body under an applied stress. The duration of the stress is very important in determining strain behaviour. Most geologic strain rates are relatively low, with stresses applied over millions of years, leading to a great reduction in yield strength. Evidence for geologically high strain rates is provided by pseudotachylite glasses whose formation results from ‘instantaneous’ frictional melting during deformation.
Subjects: Earth Sciences and Geography.