late 13c., from Anglo-Norman valey, Old French valee "a valley," from Vulgar Latin *vallata, from Latin vallis "valley," of unknown origin. Valley Girl (in reference to San Fernando Valley of California) was popularized 1982 in song by Frank Zappa and his daughter. Valley of Death was anglicized in Middle English as Helldale (mid-13c.).
A long, narrow region of low land between ranges of mountains, hills, or other high areas, often having a river or stream running along the bottom. Valleys are most commonly formed through the erosion of land by rivers or glaciers. They also form where large regions of land are lowered because of geological faults.