Two depositional sequences related to sea level changes are described and dated for two nelghborough beaches in Cantabria (Northern Spain). The oldest unit is a beach sequence consisting of basal gravels, clays and eolian sands. The aminoacid racemizalion analisis of two types of mol uses show a discrepant age (77 570 + 73 400 and 21 140 ± 9 400 y BP). Outcrop data and general sea stages arrangement , however, allows us to support a preglaciar age for this beach level. The second unit incises at least three meters in the older one and consists of peat deposits with tree stems and organic matter rich clays, representing an estuarine plaine. Radiocarbon dating gives an age of at least 6 210 ± 85 y BP for it and can be interpreted as the postglacial sea rise level