Valley of the Kings rains. There is currently little year-round rain in this part of Egypt, but there are occasional flash floods that hit the valley, dumping tons of debris into the open tombs. The quality of the rock in the Valley is inconsistent, ranging from finely-grained to coarse stone, the latter with the potential to be structurally unsound. The occasional layer of shale also caused construction and conservation difficulties, as this rock expands in the presence of water, forcing apart the stone surrounding it. It is thought that some tombs were altered in shape and size depending on the types of rock the
Exploration of the Valley of the Kings first modern map of the valley itself, in 1743. In 1799, Napoleon's expedition (especially Dominique Vivant) drew maps and plans of the known tombs, and for the first time, noted the Western Valley (where Prosper Jollois and Édouard de Villiers du Terrage located the tomb of Amenhotep III, WV22). The "Description de l'Égypte" contains two volumes (out a total of 24) on the area around Thebes. European exploration continued in the area around Thebes during the 19th century, boosted by Champollion's translation of hieroglyphs early in the century. Early in the century, the area was visited by Belzoni, working for