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
Valley of the Kings as unimportant by previous investigators. The West Valley tombs often carry the prefix "WV", but they follow the same numbering system. Some of the tombs are unoccupied, others remain unidentifiable as regards to their owners, and still others are merely pits used for storage. Most of the open tombs in the Valley of the Kings are located in the East Valley, and this is where most of the tourist facilities are located. The Eighteenth Dynasty tombs within the valley vary quite a bit in decoration, style, and location. It seems that at first there was no fixed plan. The tomb