The evolution of geology as an independent science can be envisaged as a relatively continuous process yet marked by three fundamental steps. These represented singularities which established significant advances in the epistemological and heuristic power of the discipline. This interpretation of history has to be strictly based on an evaluation of the epistemological basis of geology according to modern scholarship. The recognition of these 'golden spikes', albeit artificial, may help geologists to better grasp the philosophical position of geology with respect to other sciences. The first step was the publication of Steno's Prodromus in 1669, which established the methodological rules for decoding a geologic history from the geometrical arrangements of beds. The second step was the founding of the Geological Society of London in 1807, an act by which a new community recognized itself as a scientific and professional entity applying a novel methodology in the study of Earth. Their approach represented a synthesis of the Wernerian-historical and the Huttonian-causal methods. The third step was the emergence of plate tectonics in 1967, when the actualistic method (i.e. uniformity of laws and processes) could be extended to the interpretation of the whole lithosphere. At the same time, the heuristic power of historical geology was validated by independent, physico-mathematical testing.