更新统下界的半世纪之争

更新统下界的厘定从１９４８年提出任务，１９８４年建立意大利Ｖｒｉｃａ国际层型剖面(界线年龄为１．８Ｍａ)，到１９９８年界线下移(到２．５Ｍａ)的建议未获通过，国际争议前后延续了半个世纪，迄今仍未平息。问题的实质在于新生代最晚期缺乏全球性的重大生物演化事件，而且与其它地质时代不同，第四纪的陆相地层具有特殊的重要性。

LOWER BOUNDARY OF PLEISTOCENE: DEBATE OVER A HALF CENTURY

The lower boundary of the Pleistocene has been a subject of international debate over a half century, and it remains an unsolved question. The task to define the boundary was raised in 1948, and the international stratotype was established at Vrica, Italy, in 1984, with the boundary age of 1.8Ma. In 1998, an attempt to lower the boundary to 2.5Ma failed. The core of the lower boundary problem is the fact that there are no world--wide major biological evolution events in the latest part of the Cenozoic, and non--marine deposits are of particular importance for the Quaternary, in contrast to other geological periods.