The earth's chemical activity

The earth by all means can be considered as a very active chemical factory, which was homogeneous during its initial phase and has differentiated with time into a core, a mantle and a crust. These all are haloed by the atmosphere. Dupre and Hamelin in 1988 formulized the development history of this planet using radioisotopes. At the very begining the homogeneous mantle was agitated by intensive convection currents. This has led, in the long term, to the differentiation of the core and the mantle through accumulation of the heavy elements in the lower parts (core) and floating the light elements in the upper ones (mantle). The continuation of the differentiation and degasing processes in the newly formed mantle led to the formation of the earth crust in a similar way of preparing an immense soup pot on a light fire over 4.5 billion years. 35 refs., 4 figs