Abstract: İn this study, the formations which crop out around Ilgaz-Çankırı and previously defined as Dumlupınar and Susuz formations,have been renamed as Sarialan formation based on the lithologic paleontologicalproperties and stratigraphicalpositions.Sarialan formation overlies in uncorformity with the Permo-Triassic aged Karakaya Unit that is base rocks. Sarialan formationhas been dividedand difined in  three members as Kimmerician-Lower Tithonian aged Dumlupınar, Upper Tithonian-Lower Valanginian aged Dodaş and Upper Valanginian-Hotrivian aged Beylerbeyi.The formation consits of sandy limestone, alternation of sandy limestone-limestone with marl interbeded, micritic limestone, lesssandy-clayey limestone and alternation of sandstone-silt stone-marl with pelagic limestone and volcanics materials.Sarialan formation formed in Tithonicfades and contains abundant Calpionellids and it comforms with overlying BarremianCampanian aged Çırdak formations.