During Pliocene and early Pleistocene, the climatic evolution of north-west mediterranean lands, deducted from palynological and macroflora analysis, is characterized by successive decreases in moisture with two chief events respectively dated from 3,2 millions years ago (progressive installation of summer dryness and resulting forest clearing) and 2,3 millions years ago (first dry period with development of steppic associations). Subsequently, humid phases (deciduous forests) alternate with dry phases (open steppes), in agreement with interglacial and glacial periods. Consequently, the reference to a transitional period between Pliocene and Pleistocene is not justified.