The purpose of this paper is to elucidate the semantic relation between continental drift and plate tectonics. The numerous attempts to account for this case in either Kuhnian or Lakatosian terms have been convincingly dismissed by Rachel Laudan, who nevertheless acknowledged that there was not yet a plausible alternative to explain the so called “geological revolution”. Several decades later, the epistemological side of this revolution has received much attention, while the semantic relation between drift theory and plate tectonics has remained (...) mainly unexplored. In studying this case under a new light, the notion of embedding, as distinguished from other sorts of intertheoretical relations :11–27, 2011), will have a particular significance. After formally analyzing the relationship between continental drift and plate tectonics, it will become evident that the models of drift theory are part of the models of plate tectonics, thereby fulfilling the conditions for embedding. All theoretical concepts from drift theory are presupposed in some theoretical concepts from plate tectonics, and all empirical concepts of the former are shared by the latter. Furthermore, all the successful paradigmatic applications of continental drift are also successful applications of plate tectonics. As a consequence, under the label “geological revolution”, we actually find a salient historical case of cumulative progress across theory change. (shrink)