地质历史时期形成,后因河流他移而废弃的河道。引起河流改道可因构造运动抬升或下降,冰川、崩塌、滑坡将河道堰塞,或因人工另辟新河等原因。构造运动可使河流大规模改道,构造抬升可使废弃河道露出地面,而下降的因堆积作用旺盛,将河道掩埋,形成埋藏型古河道,如中国华北平原地下埋藏着古黄河、古海河等古河道。河流本身作用引起的改道多发生在平原地区,由于堆积作用旺盛,使河床逐渐淤浅升高成为地上河,当河流决口后,河流循新槽流去,原河道被废弃成为古河 Geological history of the formation of the river because of his removal and abandoned the river. Cause diversions can be caused by the tectonic movement of uplift or decline, glaciers, landslides, landslides will be the river barrier, or because of artificial new river and other reasons. The tectonic movement can make large-scale diversion of rivers. The tectonic uplifts can expose the abandoned river courses to the ground, while the descending accumulation of river courses buries the buried ancient river courses. For example, the ancient Yellow River and the ancient Haihe River are buried underground in the North China Plain Road. Due to the diversion of the river itself, it occurs in the plains. Due to the strong accumulation, the riverbed gradually becomes shallow and rises to be a river above the river. When the river breaks off, the river flows backward and the original river is abandoned to become the ancient river