Abstract: Erencik formation, outcropped in the southeastern Niksar (Tokat) and the surrounding area, is the typitcal formation which is representing the continuity on the Cretaceous/Tertiary boundary. This formation is characterizedby the yellowish gray, thin to medium dedded limestones and clayey limestones containing three microfacies from bottom to the top: Biosparite with intraclast, biosparite with Miliolidae, micrite with fossils. At the bottom of Erencikformation, there are the beds containing Maastrichtian benthic forams (Assemblage I) and followred by the benthic foraminifers of Danian as Laffitteiiia bibensis Marie, Laffitteina aff. bibensis Marie, Idalina aft sinjaricaGrimsdale, Scandonea aff. samnitica De Castro, Rotalia cf. perovalii Terquem, Kathina cf. delseota Smout,Anomalina sp„ Eponides sp., Planorbulina sp, (Assemblage II), The systematic characters some of the foraminifers are also given and the formation is thought to be the deposited in a fore reefal to lagunar environment.