Sediments of Hayyan formation is exist as outcrop in central part the southern range of Palmyrides chain. Their location at jabal AL - Naqnaqieh, Al-Abtar, Hoshroum, Hayyan and Jabal Al –Mazar. The Hayyan formation divided in two major parts: A- The lower part: consists of clay and marl clayey range color from gray to black gray and intercalations with gypsum and anhydrite beds, at the base of this part contain salt deposits in Jabal Hayyan location B- The upper part: consists of thick to massive beds of gypsum with intercalations beds of clay. The palynological result show that the Hayyan formation related to Middle Triassic (ladinian) - Upper Triassic (lower Carnian) while it was considered Upper Triassic (Carnian –Norian).