对泥河湾地层的认识与划分

泥河湾地层之命名乃巴尔博(C.B.Barbour)、桑志华(E.Licent)、德日进(P Teillhard de Chardin)等人于1924-1926年在我国河北省阳原县泥河湾一带进行新生代地质调查时所定。当时认为其时代属保德期之后黄土期之前。

SUBDIVISION AND RECOGNITION OF THE NIHEWAN STRATA

The Nihewan strata, a type for the Early Quaternary in North China, are worthy of further subdivision. Based upon recent field observations in connection with the previous results this article gives the following suggestions on their subdivision.On the basis of the contact between the Nihewan strata, their lithological assemblages, climatic conditions and fossil remains, three parts can be distinguished in ascending order as follows.The first part is composed of sub-sandy soil with light brown-red sandy gravel and sand lenses about 5-10 m in thickness, unconformably overlying the Pliocene Pro-boscihipparion Red Clay. It is a kind of deposits of a rapid torrential facies, which were formed in the beginning stage of lacustrine confluence and contributed to a humid and cold climate.The second part consists mainly of greyish green marl with light pink clayey soil, silt and fine gravel, about 30-40 m in thickness, containing fossils as Equus Sanmeniensis; Proboscihipparion sp., Lamprotula and etc. It is a product of dry and cold climate and possesses a horizontal thin stratification.The third part is built by greyish yellow and brown mild sendy soil, sendy gravel, calc slate sandy layer and drusy gypsum layer with oblique and cross-bedding, about 40-60m in thickness. It belongs to fluviolacustrine deposits accumulated under semi-arid climatic condition and during the time of shrinkage of lakes and concentration of calcium in deposits.The described first and second parts could be placed in Lower Pleistocene, and the third part in Middle Pleistocene. From this subdivision it can be seen that the Nihewan strata involve not only the Lower Pleistocene, but also the Middle Pleistocene even the Upper Pleistocene. Therefore our subdivision differs from the previous opinion which regards the Nehewan strata represented only as Lower Pleistocene.