Temperate and cold stages comparable to those of the last interglacial-glacial have alternated for ca. 2.4 Ma, a time-level regarded as the base of the Quaternary. A curve showing climatic fluctuations according to a number of glacials, interglacials, and temperate oscillations of small amplitude or short duration (interstadials) is given, and the value of pollen records in this context is discussed. Because the position of the individual intervals with known vegetational development on the total timescale is controlled by superposition, the lithostratigraphic position of some of them is reviewed. Basic differences in vegetational evolution between the Tiglian, Waalian, and later interglacials, as well as the extinction of certain trees at around the time of the transition of the Early-Middle Pleistocene, probably indicate lower temperatures during the glacials which have occurred in the past million years. Although the established record shows some resemblance to the oxygen-isotope curve of the deep sea, precise correlation is not yet possible. A tentative correlation is discussed.