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根据北京西山东麓的周口店、北安河两地区附近的上新世唐县期山麓侵蚀剥蚀面的变形,和中更新世周口店期洪积扇扇顶及山麓线在两地的高度差,以及晚更新世清水期永定河、大石河的侵蚀谷在毗邻山麓的山前平原埋藏深度的差别,加上永定河古河道位置的移动顺序和永定河冲积扇位置的迁移等多项标志,证明除了山地与山前平原之间存在差异性升降运动之外,山地内南部周口店地区与北部北安河地区在抬升幅度和速度上也存在差别,后者大于前者,而且自中更新世以来这种差别日益显著。山前平原永定河冲积扇形成于末次冰期的主要寒冷阶段。古河道和新老洪积扇都证明,山前平原北部存在向南翘起的趋势。从北京西山出现的这种新构造活动的差异特征,推测存在来自太行山南部向北推挤的新构造应力场。
According to the deformation of the eroded and eroded surface of the Piedmont foothills of the Upper Pleistocene in the vicinity of Zhoukoudian and Bei’an Rivers in the east of Beijing’s Xishan Mountains and the height difference between the top and the foothill of the alluvial fan in the Zhoukoudian Period of the Middle Pleistocene and the late During the Pleistocene, the difference between the buried depths of the eclogitic valleys in the Yongding River and the Dashi River near the foothills, along with the movement sequences of the ancient rivers in the Yongding River and the migration of the alluvial fan in the Yongding River, There are also differences in the magnitude and speed of uplift between the Zhoukoudian area in the south of the mountainous area and the Bei’anhe area in the north, with the former being larger than the latter, and the difference has been increasingly significant since the middle Pleistocene . The Yongding alluvial fan formed in the main cold stage of the last glacial period in the piedmont plain. Ancient rivers and new alluvial fans have proved that there is a tendency of tilting southward in the northern part of the piedmont plain. The differences in this neotectonic activity that emerged from the western part of Beijing suggest that there is a new tectonic stress field pushed northward from the southern part of the Taihang Mountains.