Abstract: The rock units, in the study area are divided in two groups as autochthonous and allochthonousunits. The oldest rock of the autochthonous units is Erenler limestone of Cretaceous. This unit is overlain disconformably by Kızılkırma formation of Paleocene-Eocene, Yazır formation of Aquitanian covers Kızılkırma formation asdisconformably and its main lithology is reefal limestones. This formation is overlain by comformably by Ağlasun formation of Burdigalian. Ağlasun formation consists mainly of sandstone and shale.In the Middle Miocene, Akdağ limestone unit and ophiolitic melange are thrusted and overlies tectonically ontoAğlasun formation. This event is the most important tectonic feature in the region and this resulted of many folds andfaults.The basement rocks and the overthrust faults is overlain by Gönen conglomerate which is post orogenic and molasse type of Middle Upper Miocene.In the late Miocene-early Pliocene transition, the Gölcük volcanism activity starts in the region. Gölcük formationis formed result of this volcanic activity. The volcanic activity in the area, progressed, in two different stages. Result ofthe early volcanic stage, andesite lavas are spread of around the Gölcük area and result of the late volcanic stage, tuff andpyroclastic materials are spread of around the Gölcük area.The upper most unit is alluvium of Quaternary.