Exploration of the Valley of the Kings 16 tombs to the list, and explored several tombs that had already been discovered. During this time Georges Daressy explored KV9. When Gaston Maspero was reappointed to head the Egyptian Antiquities Service, the nature of the exploration of the valley changed again. Maspero appointed Howard Carter as the Chief Inspector of Upper Egypt, and the young man discovered several new tombs, and explored several others, clearing KV42 and KV20. Around the turn of the 20th century, the American Theodore M. Davis had the excavation permit in the valley, and his team (led mostly by Edward R. Ayrton) discovered several royal
Valley of the Kings World Heritage Site, along with the rest of the Theban Necropolis. Exploration, excavation and conservation continues in the valley, and a new tourist centre has recently been opened. The Valley of the Kings is situated over 1,000 feet of limestone and other sedimentary rock, which form the cliffs in the valley and the nearby Deir el-Bahri, interspersed with soft layers of marl. The sedimentary rock was originally deposited between 35–56 million years ago during a time when the Mediterranean Sea sometimes extended as far south as Aswan. During the Pleistocene the valley was carved out of the plateau by steady