472 EMERSON— RECURRENT TETRAHEDRAL DEFORMATIONS. 



active forces and like the action of rotation in deflecting rivers prove 

 effective when the other forces are balanced against each other.-^ 



The continuous escape of juvenile waters suggested by Suess 

 may have promoted shrinking and have thus aided in regularly in- 

 creasing the depth of the ocean basins. 



And only part of this juvenile water may have been absorbed in 

 the hydration of minerals so that the amount of the ocean waters 

 may have increased. We may also accept the conclusions of Walther 

 that the earlier oceans were shallow and that the great and in- 

 creasing deepening of the great permanent ocean bodies which the 

 tetrahedral theory demands began with the Triassic, since all pale- 

 ozoic survivals were shallow water forms. 



Indeed the slow process by which the agglomeration of plane- 

 tesimals condensed into a globe of double the rigidity of steel would 

 permit the postulated repeated recurrence of periods of tetrahedral 

 deformation and spheroidal collapse, at first barely discernible 

 among the other deforming agencies but gradually becoming rela- 

 tively more important until at last in the grand Tertiary cycle the 

 deformation should be so great as to cause the final stage of the 

 movement of the pole to its present place and impress the strong 

 tetrahedral features on the face of the present earth. 



Finally one might say there is a certain three-fold hierarchy in 

 earth movements — orogenic or mountain making; epeirogenic or 

 plateau making; tetrahedrogenic or continent making. 



25 It should be distinctly borne in mind that the tetrahedral deformation 

 is not a crystalline action any more than is the formation of hexagonal trap 

 columns. Indeed the tetrahedral deformation of a spherical mass is exactly 

 like the hexagonal deformation of an extended mass. Both are governed by 

 the law of least action in a very similar way. There are isometric tetrahedral 

 crystals and there are six-sided hexagonal crystals. They are often perfect 

 and perfectly embody a physical law. The other cases represent a tendency 

 and act only when the remaining agencies are balanced and should be judged 

 by their best results. One should no more overlook the tetrahedral tendency 

 because it is often imperfectly realized than the hexagonal tendency in all 

 shrinking bodies. 



