Figure 1-- Temperature fluctuation (mean annual temperatures) in central Europe Tertiary time, the past 60 million years. Except for a peak in early Eocene time, temperature decreased throughout the Tertiary. Beginning in late Pliocene/early Pleistocene time, with the onset of glacial conditions, temperatures fluctuated widely, ranging from full glacial to interglacial conditions. The modern condition is approximately +4 to +5ºC. Modified and adapted from Anderson and Borns (1997).