Final answer:
The theory that combines continental drift and sea floor spreading is Plate Tectonics. It explains continental movements, mountain formation, and serves as Earth's cooling system. Initial concepts by Wegener and Hess developed into the unified plate tectonics theory widely accepted today.
Step-by-step explanation:
Theory of Plate Tectonics
The theory that combines the ideas of continental drift and sea floor spreading is known as Plate Tectonics. This theory explains how the slow motions within the Earth's mantle move large segments of the crust, which leads to the drifting of continents, the creation of mountains, and large-scale geological features. Plate tectonics is a fundamental principle in geology akin to evolution in biology or gravity in physics. The theory serves as Earth's cooling mechanism, efficiently transporting heat from the interior out to space. It was developed from Alfred Wegener's continental drift hypothesis and Harry Hess' sea floor spreading hypothesis.
Wegener proposed that continents once formed a giant supercontinent called Pangea backed by evidence such as the jigsaw-puzzle fit of continents, matching fossils, and similar mountain ranges on separate continents. However, his theory lacked an explanation of the driving forces of continental movement. It was later, with the introduction of Hess' concept of sea floor spreading in the 1960s, that a complete mechanism for plate tectonics became widely accepted by the scientific community.
Plate tectonics also accounts for other phenomena like continental rifting, where a landmass splits apart forming new continents. This process is observed in areas such as the Recôncavo basin in Brazil, illustrating the stages of continent separation. Furthermore, the theory has informed our understanding of mountain-building events, known as orogenies, which have shaped features such as the Appalachian/Caledonide Mountains through multiple tectonic occasions such as the Taconic, Acadian, and Alleghenian orogenies.