Geographers have always regarded space and time as fundamental attributes of reality. However, signi®cant variations have existed in the meaning associated withthese concepts. The independence of space and time, where each concept provides a separate frame of reference for positioning objects and events, is seen in both regional studies and in attempts to cast geography as a purely spatial science. In contrast, the
merger of time and space into the singular notion of time±space has for many researchers become the ideal in concept if not in practice.