A Hyalinea-balthica (marine foraminifera) assemblage was found by authors in cores taken from the base of Quaternary Shunyi county and other localities. Its study reveals an ingression taking place by Early Quaternary in area concerned. Taking the paleomagnetic data into accout the local subdivision of the Cenozoic is worked out as follows: Pliocene Shunyi Formation (N2sh); Pleistocene Xiadian Formation (Q1x), Zhaili Formation (Qzzh), Junying Formation (Q3J) and Holocene Series(Q4).In this paper the lithologic, petrographic and paleontologic characteristics of the Pliocene Shunyi and Pleistocene Xiadian Formations are described in details. The Pliocene-Pleistocene boundary is placed at the base of the index beds composed of marine sands containing the Hylinea-balthica assemblage and may be correlated with the level of the Matuyama-Gauss polarity change (2.43 m. y. B. P.).
. 1979, 北京平原区上新统一更新统的划分. 地质科学, 14(4): 342-349.
. SUBDIVISION OF PLIOCENE-PLEISTOCENE SERIES IN BEIJING PLAIN[J]. Chinese Journal of Geology, 1979, 14(4): 342-349.