柯林斯詞典alluvial fan (also alluvial cone) 1. N a fan-shaped accumulation of silt, sand, gravel, and boulders deposited by fast-flowing mountain rivers when they reach flatter land 沖積錐; 湍急的河水到達平地后形成的由泥、沙、石、卵組成的錐形沉積物 返回 alluvial fan