近几十年来,人类对现代地球的活动已有比较好的认识。但是,我们对于地球是怎样形成的认识却是极其初步的。关于大陆、水圈、地幔和地核是怎样和何时演化成现在的状况,我们知道得都太少了。尽管地质记录至少能帮助我们后推到38亿年前,甚至可以到43亿年前,但我们也仅能得到有关年轻地球的性质和构造作用的很不完整的概念。地球科学所面临的最基 In recent decades, human beings have had a better understanding of the activities of modern Earth. However, our understanding of how the earth is formed is extremely preliminary. We know too little about how and when the continents, hydrosphere, mantle and core have evolved into the present. Although geological records can at least help push us back to 3.8 billion years ago and even to 4.3 billion years ago, we can only get very incomplete notions about the nature and tectonics of young earth. Geosciences are facing the most basic