The precise axis of the Al Hilal anticline core is discovered at the mouth of Wadi al Qalah and along the Wadi al Qalah course at Ras el Hilal region in northeastern Libya. The newly discovered Al Hilal anticline axis is re-plotted on the structural map which was delivered earlier by El-Amawy et al. (2011). The Al Hilal Formation which represents the oldest rock unit in the coastal region of Al Jabal al Akhdar is exposed by the anticlinal fold. On the other hand, the Ghwt Sas anticline was responsible to the cropping out of Baniyah Formation (“the lateral equivalent of the Al Hilal shale”) in the central part of Al Jabal al Akhdar. Nine samples were collected from the mouth of Wadi al Qalah (the anticline core) and nearby, allowing for the revision of the previous foraminiferal biozones. The retrieved foraminifers from the processed samples were predominantly planktic assemblage belong to the oldest Concavatutruncana concavata biozone (early Santonian) in the mouth of Wadi al Qalah, and the C. asymetrica biozone (late Santonian) represents the upper biozone inside the course of Wadi Al Qalah valley. This study confirms that the older biozones recognized earlier in the area by Barr and Hammuda (1971) and Barr (1972) are not proved at the oldest exposed part in the anticlinal core.