Egypt's prehistoric sites are at risk from tourism. Experts believe that if urgent measures (1) ..., no prehistoric sites in Egypt (2) ... unharmed. Many prehistoric sites in the desert have already been lost to development projects. Now tourists (3) ... the country's remaining prehistoric sites faster than scientists can save them. In the far southwest of the desert is the "Valley of Pictures'. Two main caves in the valley (4) ... hundreds of paintings that date from between 7000 and 5000 BC. According to archaeologists, tourists (5) ... water over the figures to make them easily visible. Water (6) ... the surface of the paintings to break off in small thin pieces. "The paintings (7) ... in no time, says one expert. He adds: "The desert is under threat. This area has to be conserved."