侯家窑遗址是目前国内外综合研究水平较高的旧石器遗址之一。恢复和重建遗址形成时期的气候和环境背景,对还原侯家窑人生存条件,理解古人类进化过程和行为具有重要意义。最新的地层学、年代学和古生物学综合研究显示:侯家窑人生活在距今2413万年,下文化层属牛轭湖相沉积,由泥河湾古湖退却和消亡过程中形成的冲沟或水道被随后发育的NNWSSE向古河流切割阻塞形成;上文化层对应于后期发育的古土壤层。距今138万年,遗址区被冲洪积层掩埋。轨道参数引起的太阳辐射量变化是导致研究区气候变化的主要驱动因素;孢粉资料显示,研究区古气候、古环境经历了明显的冷暖交替过程,与北半球中低纬度地区具有较好的一致性: MIS 7阶段气候相对温和,植被景观为稀树灌丛草原;MIS 6阶段气候寒冷,年均温较现今下降3℃4℃,发育典型的针叶林植被;MIS 5阶段气候温暖,植被景观为针阔叶混交林草原。侯家窑文化经历了由温和向寒冷的气候变化,表明寒冷的气候条件并未导致侯家窑人灭绝,相反在一定程度上促进了侯家窑文化的进步;MIS 5阶段以来,河流作用破坏了侯家窑人原有的生存条件,是导致侯家窑文化中断的主要原因。
英文摘要:
Houjiayao Relic Site is one of the most important Paleolithic sites both locally and internationally,which plays a significant role on human evolution in North China.Paleoclimate and paleoenvironment reconstruction of Houjiayao Site is the basis for restoring the living conditions of Houjiayao Humans,and also the great significant for understanding the process of ancient human evolution.The latest evidences of stratigraphic, chronological and paleobiological data suggest that the ancient people lived at Houjiayao Site during 240 to 130ka BP.The lower cultural layer belongs to oxbow lake deposition which was formed by a water-channel appeared during the ancient Nihewan lake shrinking and disappearing,and clogged by a NNW-SSE ancient river.The upper cultural layer was formed by soil sedimentation corresponding to palaeo-soil layer.The fluvial layers were deposited by the riversfiller,which were formed from 85 to 130ka BP.Earths orbit forced insolation is the dominant contributor to climate change in the study area;Pollen data suggested that the study area has experienced warming and cooling cycles,which is accordant with mid-low latitude regions in North Hemisphere:during MIS 7,the zonal vegetation was forest and steppe,the climate was temperate; in MIS 6,the annual average temperature was 3 4°C lower than present,and a mixed coniferous and broad-leaved forest dominated by pines and spruces might have developed around the site;in MIS 5,the climate was warm,the vegetation landscape was mixed warm coniferous and broadleaved forest and steppe.Houjiayao culture has experienced paleoclimate evolution from warm to cold,which suggests that cold climate conditions didnt lead to the extinction of Houjiayao Human, but promoted the progress of Houjiayao culture to a certain extent;During MIS 5,fluvial processes destroyed the living conditions of Houjiayao site, which caused the interruption of Houjiayao culture.