118 MISCELLANEOUS GEOLCXJICAL CONSIDERATIONS 



'organic' compounds with optically active surfaces of quartz grains. 

 This is the fact that the sunlight, after having passed through the 

 atmosphere, shows right circular polarization. Theoretically a selec- 

 tive destruction of dextro-iorms of early 'organic' compounds in the 

 'thin soup' by the sunlight seems possible. This would leave us with a 

 predominance of laevo-active forms, leading to early life. 



Again, we do not know the actual processes. The optical activity, 

 and other elements of asymmetry present in modem life are, how- 

 ever, difficult to visualize without complicated reaction chains of the 

 type indicated above. In these reactions the availability of the opti- 

 cally active surfaces of quartz grains, present everywhere, may well 

 have been of great consequence. 



GEOCHEMICAL INVENTORIES 



As has been remarked in the introductory lines to this chapter, there 

 is yet quite a different branch of natural science that may be drawn 

 upon to find arguments for or against the new theories concerning 

 the origin of life through natural causes. This is geochemistry. Geo- 

 chemistry draws up global estimates for the abundance of certain 

 elements of the earth's crust. 



It is from such global inventories that formal conclusions might 

 be drawn. The best example for our problem is the presence of free 

 oxygen in our atmosphere. Earlier astronomical theories explained 

 this fact by assuming a dissociation of water into hydrogen and 

 oxygen. There is water enough available in the oceans. Its quantity 

 is even so vast that the loss through dissociation to form all present 

 free atmospheric oxygen would hardly be noticed. In this view, the 

 hydrogen formed by dissociation would have escaped from the atmos- 

 phere into space, whilst the heavier oxygen had been retained. In 

 contrast, we now postulate a biogenic origin of this same quantity of 

 oxygen formed through dissociation of carbon dioxide. Is this at 

 all possible? Has there ever been sufficient carbon dioxide present in 

 the atmosphere and hydrosphere to supply all this free oxygen? And 

 what happened to the carbon fixed by the plants, produced at the 

 same time the free oxygen was released? Is the amount of fossil 

 carbon, both in coal and oil, anywhere near comparable to the free 

 oxygen formed? Geochemistry, in theory, should be able to supply 

 the answers to these questions. 



