From Longman Dictionary of Contemporary Englishrift valleyˈrift ˌvalley noun [countable] SGa valley with very steep sides, formed by the cracking and moving of the Earth’s surface
Examples from the Corpus
rift valley• Upland masses exist on either side of a central rift valley.• Further evidence contradicting the traditional symmetric rift valley model comes from observations of their morphology and surface structure.• Luisenlund Bronze Age monoliths and the rift valley of Ekkodal. 