stored with the Museum of Lebanese Prehistory. Jeita IV (Mugharet-el-Mal) is a rock shelter in the cliff upstream from the grotto. It once contained a large quantity of Paleolithic material which has been looted and was deemed unfit for excavation by Sami Karkaby, Director of the Caverns in 1965. Study of the lithic remains at this shelter were hoped to shed further light on the Paleolithic or Mesolithic communities that inhabited the different sites at different times. Geology The Jeita grotto is located within the Lower-Middle Jurassic strata of Keserouane which has a stratigraphic thickness of and consists of dolomite and micritic limestone. The Keserouane formation was exposed to air by a local uplift during the Late Jurassic-Early Cretaceous. The Keserouane strata became karstified after its aerial exposure and then was buried during the Cretaceous. In the Neogene, upon the final uplift of Mount Lebanon, this early karstification phase was reactivated. At the Nahr al-Kalb valley, the impervious Upper Jurassic volcanic rocks and Lower Cretaceous sand slant almost vertically forming a hydrogeological barrier and forcing the outlet of the Jeita underground river to the surface. This barrier could be the reason for the westernmost, large cave chambers with heights exceeding . Karstification of the Keserouane limestone was further intensified by the steep topography of the area and the volume of precipitation over the Lebanon (more than 1200mm). A ratio of total slope gradient of 1/100 is calculated between the entrance of the cave and its inland extremity. This shows its smooth flat course even though it is sometimes interrupted by several small cascades and rapids. From the west, the Jeita cave starts with large halls and meanders. Through some rapids, the dimension becomes narrower. Going forth, it is spacious with the Thompson's cavern ( long and wide), Grand Chaos ( long) and Mroueh's Hall ( long and wide). The latter two are floored with collapsed blocks. The cave ends with a Y-shaped pattern, where, each branch ends with a siphon. Description The Jeita caves are solutional karst caves which have formed over millions of years due to the dissolution of limestone. The limestone is dissolved by carbonic acid charged rain water and groundwater; when the limestone, which is originally waterproof, contains cracks produced by tectonic forces the water oozes into the rock and starts to widen the cracks and solute caves inside the layers. Jeita is the longest cave complex