关键词: 地面古河道, 冲积扇, 河北平原, 洪积扇, 漳河, 滦河, 分流点, 永定河, 三角洲平原, 洼地

Abstract: In the Hebei Plain, the surface ancient channels can be divided into two types; canal-shaped surface ancient channels and elongated-highland-shaped surface ancient channels. Each of them represents the form of a certain stage in river developement. The distributional pattern of the surface ancient channels is different in different geomorphic zones; in the pluvial-alluvial piedmont fan plain zone, the pattern is fan-like; in the alluvial plain zone (middle part of Hebei Plain) the distributional pattern is parallel drainage; and, in the eastern part of the plain near the sea, the pattern is radiating like that on a delta.The ages of surface ancient channels have been determined in each geomorphic zone respectively; in the piedmont pluvial fan zone, the ages of the ancient channels include Late Pleistocene, Early and Middle Holocene; in the Pluvialalluvial fan zone, the majority of the ancient channels dates from late Holocene; and, in the alluvial plain zone and in the lowland zone near the sea (eastern and southern part of the He-bei Plain), they date mainly from historical times (since Han Dynasty), with a small part of them dating from Middle Holocene or the early historial epoch (before Han Dynasty).The distributional pattern of surface ancient channels and the change of their courses are closely related to neotectonic movement. Evidences show that the mounta-inous region on the northwestern side of the Hebei Plain has been uplifted with a greater amplitude, while southwards and eastwards the mountains have been less up-lifted. Recently, a belt joining Wen-an Depression and Tianjin City has a tendancy of sinking.