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 Carter to explore it. After a systematic search they discovered the actual tomb of Tutankhamun (KV62) in November 1922. At the end of the century, the Theban Mapping Project re-discovered and explored tomb KV5, which has since been discovered to be probably the largest in the valley (having at least 120 rooms) and was either a cenotaph or real burial for the sons of Ramesses II. Elsewhere in the eastern and western branches of the valley, several other expeditions cleared and studied other tombs. Until 2002 the "Amarna Royal Tombs Project" explored the area around KV55 and KV62, the Amarna