Reviews 



Les tremUements de terre et les systemes de deformation tetraedrique 

 de Vecorce terrestre. (" Earthquakes and the tetrahedral deforma- 

 tions of the globe.") Par M. Montessus de Ballore. An- 

 nales de Geographie, No. 79, XV, 1-8, Paris, 1906. 

 Six months ago we called attention in this Journal (Vol. XIII, 

 p. 462) to a notable paper by M. Montessus de Ballore upon the distribu- 

 tion of earthquakes. The author of that article has another in the 

 Annates de Geographie for January, 1906, upon "Earthquakes and the 

 Tetrahedral Deformation of the Globe," which is well worthy of especial 

 attention in connection with the general subject of earthquakes and 

 their distribution. Evidently the theory of the tetrahedral form of the earth 

 — a theory so much favored by M. de Lapparent and by Michel-Levy — 

 is regarded by the author as worthy of serious consideration in connection 

 with the study of the distribution of earthquakes. The following are 

 the general conclusions formulated in the course of the article: 



1. Considering the matter from a purely geographic point of view, 

 earthquakes occur about equally and almost exclusively along two nar- 

 row zones that follow two great circles of the earth: the Mediterranean 

 (or Alpino- Caucasian-Himalayan) circle, with 53 per cent, of the recorded 

 shocks, and the circum-Pacific (or Ando- Japan-Malay) circle, with 41 

 per cent, of the shocks.- 



2. These seismic zones coincide exactly with the geosyncHnal zones 

 of the secondary epoch which during the Tertiary were thrown into moun- 

 tain chains or geosynclines by the foldings and displacements. 



3. The folded structure of the geosynclines is seismically unstable, 

 while that of the tabular continental areas, on the contrary, is stable. 



4. Finally, it is concluded that the existence, well established by obser- 

 vations, of two great circles of maximum seismic unstability affords no 

 argument in favor of the theory of the tetrahedral deformation of the globe. 

 On the contrary, it would be surprising if there were no relations between 

 the earthquake regions of the earth and the elements of the tetrahedron, 

 •f such a sohd really determined the most general movements of the surface 

 of this planet. 



It may be added by way of postscript, and for the benefit of students 



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