Most of the lava tubes of Saudi Arabia are at least one million years old and their floors are almost always covered with a thick layer of sediment. In the case of Hibashi Cave this layer is up to 1.5 meters deep, consisting of very fine dust or loess (particle size 15 microns) composed mainly of quartz, feldspar and kaolinite, nearly 6,000 years old, dated by Optically Stimulated Luminescence (OSL). Studies of the sediments in Saudi Caves has barely begun...