Figure_17. Paleogeographic maps of the Western High Atlas (Morocco) during the Neogene (Upper Pliocene to Quaternary)..

Unit 2 (U2), composed of conglomerates with limestone and coastal sandstone beds to the east, transitions to a more molassic and deeper marine environment to the west. Fossil contents include gastropods such as Yetus gracilis, Planorbis, Venus excentrica, and unidentified vertebrate bones. U2 represents a regressive phase, with littoral deposits to the west and fluvial-lacustrine facies to the east, associated with tectonic uplift of the western High Atlas. Green goethite marl indicates a brief lagoonal episode before the final retreat of the Pliocene Sea. This sequence marks a regressive Pliocene, showing a gradual transition from marine to continental environments driven by tectonic and environmental changes. At the El Mhasseur site, the Quaternary is confirmed by the discovery of an echinoderm fossil, identified by Mr. Masrour Moussa, found in the sandy facies next to shell debris. This fossil helps to establish the upper limit of the Pliocene in the study area.