The Jabal Al Qarah Caves of the Hofuf Area, Northeastern Saudi Arabia: A geological investigation

The Jabal Al Qarah Caves, located approximately 13 km east of Al Hofuf Eastern Province of Saudi Arabia, are an intricate cave system developed in the calcareous sandstone, marl and clay of the Upper Miocene to Lower Pliocene Hofuf Formation. Physiographically, the hill of Jabal Al Qarah is an outlier mesa that is located at the eastern edge of the Sheagum Plateau, the southern extension of the As Summan Plateau, and the larger Syrian Plateau to the north. Based on cave morphology and interpreted evolutionary history, the Jabal Al Qarah caves appear to be significantly different from other limestone caves reported in the As Summan Plateau. Jabal Al Qarah is known for its fall, linear cave passages and narrow canyons. The boxwork of linear passages is better developed here than any other known cave locations in the Eastern Province. Field observations, including orientations of the escarpment face of the Shedgum Plateau, joints, and fractures, coupled with a review of the tectonic history of the region, suggest that these caves resulted from erosional enlargement of a series of very deep and narrow joint-controlled fissures in the Hofuf Formation. Petrographic data, especially an abundance of well-preserved palygorskite type clay minerals, suggests that the Hofuf Formation was deposited in a mudflat-dominated coastal plain environment.