_:b1215650 . _:b1215650 "ADL:FTT"^^ . _:b1215650 "A depression caused by erosion by water or ice. Low-lying land bordered by higher ground; especially elongate, relatively large gently sloping depressions of the Earth's surface, commonly situated between two mountains or between ranges of hills or mountains, and often containing a stream with an outlet."^^ . _:b1215650 . _:b1215650 .