Huang Chunchang
Through analysis of strata structure, lithological chracteristics, 14C dates and depositing environments, stratigraphical subdivision and comparison of Holocene loess are made in the Weihe River Basin within the Loess Plateau. According to the physico-chemical characteristics and weathering-soilization of the loess, sporo-pollen and vegetation, as well as river-water-level changes and the arid-humid changes of climate reflected hy the location migration of ancient cultural sites, the environmental changes of Holocene is exposed in the Weihe River Basin.That is.Q41:10,500-8500 year B.P., the Northwest Monsoon was prevailing, dust-storm and dustrain occurred often, eolian loess deposi ted(L1).Mean temperature was 6-10℃, rainfall 300-500 mm, semi-arid chimate of the Temperate zone, drygrassland vegetation.Q42:8500-6800 year B.P. the southeast Monscon was prevailing, Burozem formed in valley and Black Loesslike Soil in high plain (So-Lower).Mean temperature was 14-16℃, rainfall 700-900mm, semi-humid climate of the Subtro-pic zone, deciduous broad-leaf forest vegetation.The Cishan-Peiligang Culture arose, people lived in high land because of the threat of flood.Q43:6800-3000 year B.P., the Northwest Monsoon was prevailing, dust-storm and dust-rain occurred often, Icess deposited(Lv).Mean temperature was 8-12℃, rainfall 400-600mm, semi-arid climate cf the Temperate Zone, forest-grassland vegetation. The famous Yangshao Culture becmed pecole lived in low land near river Since drought and water shertage.Q44:5000-3120 year B.P., the Southeast Monsoon was prevailing, Burozem and Black Loesslik Soil fermed (So-upper).Mean temperature was 13-15℃, rainfall 700-800mm, semi-humid climate cf warm Temperate Zone, deciduous broad-leaf forest vegetation. Entering the Luongshan Culture and the early Zhou dynasty, people moved to high land because of the threat of flood.Q45:3120-1400 year B.P., the Norrhwest Monsoon was prevailing, dust-storm and dust-rain occurred, loess deposited (L0).Mean temperature was 8-12℃, rainfall 300-500mm, semiarid climate of th Temperate Zone, forest-grassland vegetation.The capital cities of the west Zhou, Qing and west Han dynasties in the area were all established in the low land near river because of water shortage.Q46:last 1400 years, climate has become warm and humid, modern soil is Brown Soil and Black Loess-ilke Soil (MS).Mean temperature is 10-14℃, ra-infall 600-700mm, deciduous broadleaf forest vegetation. The capital cities of the Suei and Tang dynastest were moved to high terrace because of the threat of flood and the rising of underground water-level in low land.According to this regularity of environmental changes, we can find out that there are three climatic cycles whose periodity is about 3700 years in a changing process of coldarid to warm-humid. Now we are living in the warm-humid stage of the third climatic cycle, the modern climate situation since 580 A.D. will continue for about 500 years.
