The Origin of the Biosphere 33 



The evolution of the ancient crust of the Earth 3 x lo^ years ago and earlier 

 was characterized by intensive tectonic and volcanic activity such as has not taken 

 place since. The whole world comprised a single geosyncHnal area. Limitless 

 fields of effusive material and enormous streams of lava built up the basaltic 

 shell of the Earth. Tremendous weathering processes involving the destruction 

 of the erupted materials gave rise to mighty deposits, mainly of clastic material, 

 which, as it were, acted in some places as a filter for the hot gases and magma 

 rising from the depths of the Earth. In addition, the intrusive activity became 

 even stronger at that time. Enormous masses of so-called anatectic granitic 

 bathoUths are scattered through these extremely ancient sedimentary strata. 

 Granitic material penetrates so profusely through these ancient sedimentary 

 formations of gneiss that it is hard to define the boundary between the true 

 granite and the host rocks. Thus the early Archaean granites, which are charac- 

 terized by a high content of potassium felspar, arose from the earhest sedimentary 

 deposits by their becoming molten again under the influence of heat and emana- 

 tions. Eighty per cent of all granites arose in the Archaean. The growth of the 

 granitic shell, showing an extraordinarily vast scale, was virtually finished by the 

 end of the Archaean or begiiming of the Proterozoic, i.e. about 1-5 or maybe 

 2 X 10^ years ago. 



With the further development of intrusive activity in the crust of the Earth, 

 small islands of solid land appeared in the upsurge of the Archaean surface of 

 the Earth. These constituted ancient nuclei of geological formations which can 

 be shown by methods of dating based on radioactivity to be 2-2-5 X lo^ years 

 old or more. These nuclei of continents are known to occur on almost all the 

 main land masses of the present day. These nuclei of continents have, as their 

 foundations, the earliest effusive formations (see Fig. 2). 



A turning point occurred in the history of the surface of the Earth when more 

 stable and undisturbed areas first came into being in its géosynclinal surface. 

 These gradually extended to form platforms. 



A particularly marked contraction of the géosynclinals and intensive growth 

 of the platforms may be noted at the very end of the Archaean or beginning of 

 the Proterozoic, i.e. about 1-5-2 x 10^ years ago. The crust of the Earth entered 

 into a new stage of development with the contraction of the geosyncHnals and 

 the growth of the platforms with their sedimentary coverings. The biosphere 

 and organic beings are closely associated with sedimentary formations. The 

 earliest sedimentary formations were now laid down on the basis of the persistent 

 nuclei of ancient rocks. The schists of the Keewatin formations of the American 

 continent are estimated to be more than 2-5 x lo^ years old. Schists of the same 

 type, found in Kambove in West Africa are credited with an age of more than 

 2-2 X 10^ years. The Svinion gneisses of Karelia are thought to be more than 

 2-1 X 10^ years old. The Saxagan gneisses of the Ukraine are over 2 x 10^ 

 years old. The Shamva granites of Africa are 2-8 X lo^ years old and so on 

 [7, 22]. In these, and even in more recent formations of the end of the Archaean 

 and begiiming of the Proterozoic, one may find most suggestive evidence for the 

 presence of an oxygen-containing atmosphere in the Archaean in the form of 

 sedimentary iron ores, iron-containing quartzites (the so-called jaspüites) con- 

 3 



