The oldest rocks in the Penbegˇli-Tut inlier of southeastern Turkey belong to the Meryemuşagˇi Formation (base not seen); they are mostly clastic rocks of ?late Precambrian age, overlain with angular unconformity by unfossiliferous quartzites (270 m est.) of the Zabuk Formation. The latter unit is succeeded conformably by the Koruk Formation (Lower?/Middle Cambrian), comprising almost 200 m of dolomite and grey and red nodular limestone, and the Sosink Formation (Middle Cambrian), about 600 m of silty mudstone and sandstone with a few thin limestone beds, overlain unconformably by Cretaceous carbonates. The closest comparison is with the Derik-Mardin area, 220 km to the east, where the section is more complete. The upper Koruk Formation contains trilobites of the Pardailhania and Solenopleuropsis biozones; trilobites from the Sosink Formation indicate the Solenopleuropsis Biozone, a post-Solenopleuropsis interval, and a level with Holasaphus mesopotamicus, known only from the Derik area. Acritarchs from the highest Koruk Formation and the whole of the Sosink belong to the lower part of microflora A2, described from the Middle Cambrian of eastern Newfoundland.