中国的红土期

THE RED EARTH PERIODS IN CHINA

前人仅将华南的红土分为5期[1]，且各期的起迄年龄不详。根据全国众多的红土实例及年龄资料，提出我国6个红土发育期的划分方案，从南向北，红土期数减少，历时变短。各期红土尚可分出若干个亚期，有待今后深入研究。

From the dating data of 151 samples collected from 189 profiles of red earth, the evolution of aam earth can be divided into 6 periods since late Pliocene in China, which are N2, Q1, Q, Q, Q and Q. The former four periods can be found either in North China or in South China, while the latter two periods are developed mainly in South and Southwest China, where the red earth is developing also at present.The time from beginning to end for each period shortened from South China to the midddle-lower reaches of the Yangtze River and then to North China, thus the interval between two periods lengthened from south to north. The periods of red earth were nearly successive in South China, where the environment during the whole Quaternary was suitable to the evolution of red earth. But there was less red earth since late Pleistocene in the middle-lower reaches of the Yangtze River, and the development of red earth had stopped essentially since Q in North China.The dating and lithological characters of some btypical samples of red earth for six periods in four regions are enumerated.Each main period can also be divided into several sub-periods. For example, there are 10 layers of paleosoil loess, 4～5 red layers in the cave sediments of Zhoukoudian, lower three cycles and upper three cycles, each of which is composed of red ed and yellow sandy clay, in a profile of Yejialong in Jiangxi Province, 7 layers of red paleosoil in a proile of Xuancheng in Anhui Province, and 16 layers of weathering red earth in the Quaternaly basalt Of Lei-Qiong area of South China.