Zhou Tingru
This paper deals with the conspicuous climatic changes in the Quarternary time,an alternaton of relative warm and cold periods related to transgression and regrssion of the sea. In addtion, the terrestrial influence of the Monsoon climatic circulation caused the seasonal change of landscape in the areal differenciaion at various ages. In China,three major zones can be divided: Ⅰ. East China, (North, Central, and South)with prevailing monsoon circulation, 1. Early Pleiostocene The Climate here became colder than previous age. This is indicated by plant fossils which show a gradual decline of thermo-phalic elements. It should be noted that the cold spell produced a taiga forest, with a permafrost formation in the northern portion of the Da Hinggan Mts. The northern part of China Could be divided into two zones:a) The nor-theast provinces, characterized by a moderate, warm climatet, with a mixed forest Composed of Coniferous and broad-leafed deciduous trees; and, b) North China, with a summer-green forest and grassland. Central China involves a broad belt of subtropical climate. The area was influenced by the summer monsoon rain and continental Cyclonic storms which mitigated the effects of the dry subtropical high pressure cells of the northern hemisphere. Thus, a landscape of subtropical evergreen and deciduous mixed forest formed which Can be identified by pollen analysis from the "Qutagtang" peat beds near Dongting Lake and some other localities. In south China, sediments Containing pollens of subtropical evergreen trees as well as some deciduous trees are still found in fossil assemblages. In the most southern part, the fossil remains of the basin deposits reveal the prese-nce of a tropical rain forest and tropical animals, 2. Middle and Lare Pleiostocene In North China, the well known "Peking Man" and the animal associates represent the warm stage of the early middle pleiostocene, In the cold stages, plateaus, hills were covered by a veneer of loess and sediments of different origin., In the late Pleiostocene, the polar air mass pushed southward to the northern side of the Lake Taihu where is the southern limit of the loess deposits. Owing to insufficient moisture in the Cold air mass, no glaciation existed in East China except a few high peaks in the Ice Age. 3. Holocene After the last Quarternary Glaciation,the polar ice caps diminished causing a climatic change and a rise in the level of the sea, Higher temperatures shifted the natural zones to ward the northern pole which resulted in the migration of subtropical plants and animals to the north. This climatic change is mostly determined from the changes observable in the peat beds. Ⅱ.The arid region of North-West China. This arid region stretches from Nei Monggol to Xinjiang.Humidity decreased gradually westward, along with changes of landscape, as one moves across the steppe into a desolate desert. Ancient and present glaciation occurred on high mauntains.there were about 4～5 oceurances of glaciation of which the earliest were the largest. The extention of glaciation was gradually reduced. Ⅲ.The Qinghai-Xizang High Platiau and Affiliated Areas. The vast expanse of this high area became much Colder and drier during the Quarternary time.the marginal high mountains prevented oceanic air from pene-treting the interior. Thus ia areas where glaciation had aiminished, the lakes shrank quickly as it is indicated by many shore reraces that rise above present water surface. According to the pollen data and ages of moraines, four periods of glaciation developed. The plateau has been Covered with scanty grass and rosette plants, the herbivorous animals of the region adjusted to the severe environment by developing thick fur and strong jaws and teeth in order to adapt to such a severe climate and the consequent shortage of food. It is worth noting that the upheaval of the plateau and the radical change in the unfavorable environment to human habitat on the plateau are like to. day seems to have occurred in the very late stage of the Quarternary.
