A composite lowermost Tertiary section based on lithologic and paleontologic data from three cores drilled near Paris, France, shows the Montian beginning with a bed which is transgressive on the Campanian chalk. Marked variations in thickness of the Montian beds and the partial disappearance of the upper horizons confirm the existence of a pre-Sparnacian period of erosion. The Meudon conglomerate and the overlying lignitic sands at the base of the Sparnacian are succeeded by a series of sands and shales. The Auteuil sands were deposited in deep gullies cut in shales. The thicknesses of the Montian and Sparnacian facies in the cores are compared in a chart.