TIDAL STRESSES IN THE CRUST 81 



coasts, has been among the directing forces in fixing their position and 

 determining the constant repetition of parallel or superimposed chains 

 during long geological ages (see Prinz's map, page 94). 



POSSIBLE FORMER PARALLELISM OF EQUATOR WITH MEDITERRANEAN ZONE 

 ■ AND GREATER OBLATENESS AS AN EXPLANATION OF THIS ZONE 



Presentation and discussion of views of other writers. — The tidal force was 

 assumed by Green to be capable of making fissures in the crust. Grant- 

 ing this, the necessary connection of the two sets of fissures was assumed, 

 and, while there is a possible reason for the occurrence of Assuring in the 

 vertical zone, in that it coincides with maximum bending or sedimenta- 

 tion at a coastline, there is no reason apparent why this particular posi- 

 tion of the ecliptic plane bisecting the three continents was a plane of 

 weakness rather than any other. 



Moreover, granting such a plane of weakness, the shearing force gen- 

 erated by rotation parallel to the equator, GH of figure 6, page 79, would 

 act at great and perhap sprohibitive disadvantage at an angle of 32 i 

 degrees to its proper direction in the plane EF. 



I was thus led to consider, although at the same time dismissing the 

 idea of torsion, the alternate hypothesis or speculation that this zone 

 was once the equator or parallel to the equator, the earth rotating, like 

 Jupiter, with the equator and ecliptic nearly coincident, which would 

 make these stresses a maximum both for the Mediterranean and the 

 Pacific zones. As theory does not permit to the earth so small an 

 obliquity, I pursued the inquiry without regarding the amount of the 

 obliquity, since there are many peculiarities concentrated in this remark- 

 able band which may possibly find explanation if it were an equatorial 

 zone. This would shift the pole north beneath the brass meridian to a 

 point west of Bering strait, and the center of the equatorial ring would 

 be on the line crossing northern Africa on the map in plate 14, page 78. 

 I was then interested to recall that other students, working in different 

 fields, had come upon results which demanded a transfer of the pole into 

 much the same region. 



The first suggestion of this position of the earth's axis came from 

 Kloden.* who pictured the earth as a fluid and motionless body, egg- 

 shaped from lunisolar attraction, which began to revolve slowly on solidi- 

 fication. As rotation increased the pole moved to its present position. 



Doctor J. Evans, in a presidential address before the Geological Society 

 of England,t supposes an equatorial mountain chain raised across the 

 north of Africa, crossing the meridian of Greenwich in 20 degrees north 



*K. F. Kloden : Grundlinien zu einer neuen Theorie der Erde. Berlin, 1823. 

 fQuar. Jour. Geol. Soc, vol. xxxii, p. 108. 



