Abstract: The sedimentary rocks of Mesozoic and Tertiary in the Mudumu-Göynük basin are more than five kilometers in thickness. This sequence is seen overlying granitic rocks in the south; but in the western part of the basinit can be seen either on the granitic rocks -Permo-Triassic aged rock units. First, Mesozoic sedimentation began in fower Jurassic and sandstones of Lias series deposited in the troughs ofthe paleotopography. The sea transgressed in Middle-Late Jurassic and Early Cretaceous and covered lands-earlyJurassic in the area. The eastern and northeastren parts of the basin were relatively deeper than the western part inthis phase. In the Late Cretaceous the basin reached the deepest position entirely and fiyseh sediments were depositedin the whole area. The uplifting of the southern part by the tectonic events in the end of late upper Cretaceous formedan east-west trending shoreline. The regression continued during the Paleocese and this shoreline had regressed tothe north, but shallow marine conditinos prevailed in the of this shoreline. In Early Eocene a new transgression occured, without getting much deeper the sea regressed again in late Eocene and Oligocene. The continental conditions continued until recent in the area. Some lakes formed especially in tectonical depressed areas in Miocene and Quaternary