关键词: 华北山地, 古河道, 古水系

Abstract: Two drainage patterns are found in the North China Mountains:One is a longer river system across the ranges of the Taihang Mt.and the Yanshan Mt,it initiated in the Eocene.the first episde of the Himalaya Orogenesis,and subsequently passed through the primary stage of formation in the Eocene,and lateraly windening stage in the Neogene.The internal drainages coexisted with the exterior draginages from the Early Pleistocene to the Middle Pleistocene and the lateral continuity stage was in the Middle Pleistocene.The river incising and modern drainage forming stage was in the Late Pleistocene.The other is a shorter river system origined from the east pedimont area of the Taihang Mt.and the south pedimont area of the Yanshan Mt..It started in the beginning of the Early Pleistocene,the third episode of the Himalay Orogeny,and subsequently went on incising stage in the Early Pleistocene,lateral windening stage in the Middle Pleistocene,rivers dissecting and present drainage forming stage in the Late Pleistocene.Comparing the two drainage systems,there are two different valleys in the river geomorphology.The former has a three series supPerposition-tray-like valleys,broad valleys with "U"-like and"V"-like gorges.The later has a two series superposition-broad valleys with "U"-like and "V"-like gorges.

Key words: Palaeochannel, Palaeodrainage patterns, The North China Mountains