‘Hitherto want of accuracy and definiteness have often been brought as a charge against geology, and sometimes only with too much justice’, wrote Archibald Geikie in a review of Sir Roderick Murchison'sSiluria(1867). ‘We seem now to be entering, however, upon a new era, when there will be infused into geological methods and speculation, some of the precision of the exact sciences’. Geikie's judgement echoed an appeal made some thirty years earlier by William Hopkins (1793–1866) that the science of geology needed (...) to be ‘elevated’ from a level of ‘indeterminate generalities’ to a rank among the stricter physical sciences. This paper aims to analyse, in the context of broader trends favouring measurement and mathematics in British scientific practice, Hopkins' role in the promotion of dynamical geology as a major new complement to stratigraphical geology such that, for example, in the first edition of Geikie'sTextbook of Geology(1882) the dynamical and stratigraphical components each filled 376 pages. (shrink)