Abstract: The Guanganmen area is the locality of the ancient Jicheng city (the earliest city site in Beijing). Based on the geomorphological analysis and the several kinds of experiments for the samples collected from the geotechnical profile in the construction site of Guangyi Building in Guanganmen area, the reconstructions of palaeogeomology in this area were conducted. The results show that the location of the ancient Jicheng city was just the highland, which developed since the Holocene, beside the river, where the channel of Yongding River has been passed through about 22000 years ago. The climate in this area has changed from the cool and wet environment (sparse-wood grassland was developed) and the following arid environment (grassland vegetation was developed) in the late Late-Pleistocene to the warm and wet environment (sparse-wood grassland was developed) and the following cool and wet conditions (meadow vegetation was developed) during the Holocene.

Key words: Jicheng, late stage of Late-Pleistocene, Holocene, environmental evolution, geomorphology

摘要： 广安门地区是北京最早的城址?? 古蓟城所在地。对广安门内的广义大厦工程地层剖面进行的古地貌复原研究表明, 当地在2.2万年前为永定河河道, 全新世以来发育成河旁高地, 成为古代蓟城的选址地。经历了由晚更新世晚期较冷湿的疏林草地、较干旱的草原植被景观、全新世较暖湿的疏林草地及较凉湿的草甸植被环境的演变过程。

关键词: 蓟城, 晚更新世晚期, 全新世, 环境演变, 地貌