The Kuhlan Red Bed Formation in NW Yemen contains different types of sediment layers that reveal clues about how they were formed. The researchers identified three main groups of sediment types, showing evidence of deep marine shelf conditions, glacial activity, and shallow marine shelf environments. The rocks in the formation are mostly made up of sandstone, siltstone, shale, and other materials like quartz and iron oxide. The layers suggest a mix of deposition from turbidity currents, glaciers, and marine transgression. The study helps us understand the history of this area and how these rocks were formed over time.