Study on stratigraphic age, climate changes and environment background of Houjiayao Site in Nihewan Basin

Stratigraphic and chronological researches on the profile of the Houjiayao Site show that the cultural layers were shallow water oxbow lake deposits in front of fluvial fans before emergence of the Liyigou Stream, which were formed during the period of 160 to 220 ka; the fluvial layers were deposits from rivers’ filler on fluvial fans, which were formed from 85 to 160 ka. The pollen data shows that the vegetation in the vicinity of the Houjiayao Site succeeded from temperate grassland to mixed coniferous and broad-leaved forest, and then forest steppe; the climate changed from temperate and dry to cold and wet, and to temperate and humid. Houjiayao Man lived in MIS 6 with a cold climate. The vegetation at that time was mixed coniferous and broad-leaved forest and there was a shallow water oxbow lake adjacent to the site, which was an ideal place for survival of various animals. Rich animal and plant resources were the main source of food for Houjiayao Man. In the Palaeolithic, with low productivity and shortage of food, Houjiayao Man preferred a sufficient food source area for settlement, which indicates that Houjiayao Man had learned to withstand the cold climate.