Abstract: The Oligocene sediments occuring around of Çatalca are divided in two different rockunits, i.e., sandstone-conglomerate and marl. The pre-Tertiary basement rocks are gneiss, micaschists,marble and quarzite which are representatives of the Istranca metamorphic massif.The sandstone-conglomerate unit is composed of poorly consolidated sandstone, mudstone andconglomerates as channel deposits. Local existance of coaled plant fossils and local intersupplementarycoals are observed in the sandstone section. Sedimentological and textural properties of the sandstone conglomerate unit indicate that such unit possibly deposited in alluvial environment. Lignite occurance,observed with varying dimensions which possible deposited in flood-plainmarshes of fluvial environment.The marl unit consists of mainly clayey limestone, calceraous shale, mudstone and claystone whichshow cyclic and ordered lamination. Clastic horizons which are composed of well sorted quartz-arenitsituate in many levels in marl section. Major rock components of the marl unit, indicate a lagoonal typeshallow depositionaî environment. In addition to textural properties and lateral stratigraphic variationsof quartz-arenites, represent the existance of a beach type clastic shore plains.