80 B. K. EMERSON TETRAHEDRAL EARTH : INTERCONTINENTAL SEAS 



And this was the interesting coincidence that Green utilized. At the 

 instant when what we may call the vertical tidal stretching was causing 

 the polar circle fracture around the Pacific, the horizontal tidal shearing 

 would tend to produce ecliptic fractures along the Mediterranean zone, 

 since this lies parallel to the ecliptic when the Pacific coastline is per- 

 pendicular thereto. 



Indeed, Green assumed that if the Pacific coast was thus fractured by 

 the tidal stress (and this seemed to him certain) a set of fractures at right 

 angles thereto, or ecliptic fractures, would necessarily be formed coinci- 

 dent therewith and extended clear around the globe, and thus the twin- 

 ning plane was formed. 



The southern hemisphere, tending to move eastward parallel with the 

 equator, as explained on page 67, utilized this plane of fracture parallel 

 to the ecliptic, and moved the southern continents along it to their present 

 position, and thus the twinning plane was used. 



This furnished a consistent and extremely ingenious theory and con- 

 nected a great multitude of diverse phenomena with the tetrahedral idea* 



TIDAL STRESSES IN THE CRUST 



Although we are not able to assign an important place to torsional 

 forces and tidal stresses in the formation of the intercontinental zone, we 

 have wished to explain Green's h} 7 pothesis thus fully for the considera- 

 tion of others, because of its curious interest, and because it brings up 

 the subject of tidal stresses in the earth's crust. 



If these tidal forces have transferred the moon from a place near the 

 earth to its present position, their reaction must have been in some wise 

 effective in the earth's crust and more and more effective as we go back- 

 ward in time. . 



If this force were able, acting alone, to produce fissures, it would form 

 a close set tangent to the polar circles, and covering the face of the earth 

 like the engine-work on a watch-case, and breaking the crust up into 

 diamonds with angles of 47 degrees directed north and south. The tend- 

 ency of the tetrahedral' deformation is to produce triangular land-masses 

 with the apex southward. In combination the tidal force may tend to 

 emphasize and duplicate these southward triangles. Where the Atlan- 

 tic coast type prevails in the Atlantic and Indian oceans, coast formation 

 is largely by sinking of great land blocks, and the tidal strains may be 

 influential in choosing or directing the course of fissures otherwise caused, 

 and thus be partly responsible for the prevalence of northeast and north- 

 west coastlines. We recall India, Greenland, and the south lobes of the 

 continents. It seems also possible that this tension, acting transversely 

 to the northwest and northeast mountain chains and sharply sloping 



