We have determined both morphological and analytical soil profile and horizon development indices for seven fluvial terrace soils of Holocene to Middle Pleistocene age in relation to the sandy gravel parent material. The relationship between age of fluvial terrace soils and morphological and chemical indices of horizons and their depth indicates two main trends: (i) as soil age increases, index values tend to increase throughout the chronosequence; (ii) the degree of differentiation between the horizons of each soil becomes progressively more evident. In the Holocene soils the rate of soil formation is rapid, decreasing in soils of Late Pleistocene age. At some 100,000 years, soils reach a state of maturity. Finally, in Middle Pleistocene soils (300,000 to 600,000 years old), evolution of these Palexeralfs is even slower. Morphological and analytical indices in all these soils undergo continuous changes throughout the chronosequence without seeming to reach a steady state.