REPORT OF THE DIRECTOR 192O-2I 133 



gists that throughout geologic time it (the earth) has been losing 

 volume, due in part to the loss of heat into space, but probably in 

 greater degree to internal molecular rearrangements." 



From the great amount of this shrinking of the earth, that set in 

 after the earth had reached its mature size, or directly before the 

 Archeozoic era, and from its causal relation with recombinations and 

 recrystallization in the depths of the earth, it seems entirely proper 

 to infer that the shrinking process was most active in the earliest 

 part of the geologic history, or in the Precambrian, and that it 

 gradually will die out and thus lead to that featureless earth with its 

 universal ocean, that will mean old age for the planet. A corollary 

 of this view is that folding and its associated phenomena was then 

 also more intensive and above all more widely spread over the 

 earth than in these late days of localization of the folding process. 

 This conclusion is strongly supported by the uniform presence of 

 enormous intrusive masses throughout the world in the Precambrian 

 rocks, which in the Proterozoic of south-central Canada have been 

 estimated to have a thickness of 4 miles. 



Consideration of the facts here set forth urges adoption of the 

 view cited above that our geologic history began with a worldwide 

 contraction of the earth and the resulting worldwide intensive and 

 simultaneous folding and intrusive activity, suggested by the 

 Precambrian rocks. In that case, we must ask ourselves how did 

 the uniform trends of folding of large areas of supercontinental 

 size come about? 



Austrian and Scandinavian authors have agreed from the closely 

 contorted and crumpled condition of the Precambrian rocks in 

 their respective countries, upon a uniform contraction of the earth 

 producing a tangential pressure acting from all sides. We have, 

 however, presented ample evidence that the Precambrian folding, 

 foliation etc. show a well-marked arrangement on a huge scale. There 

 is, therefore, evidence that a uniform and probably relatively rapid 

 contraction of the earth crust in Precambrian time, while producing 

 the irresistible tangential pressure that has folded all Precambrian 

 rocks, could not have been the controlling factor of the direction of 

 folding. It has been inferred, as we have seen above, that the 

 supposed irregular folding of the Precambrian indicates the con- 

 traction of a relatively homogeneous earth crust, acted upon from 

 all sides and lacking such belts of weakness where folding would be 

 most likely to become so concentrated, as it has been in later stages 

 of the development of the framework of the earth. The amazing 

 regularity and arrangement in distinct segments of the folding of 



