The model used to determine the magnitude of the circumferential forces due to imbalance of the rotating Earth, takes into account the 'vertical force' in the direction of the 'radius of eccentricity'. This model also describes the situation that would occur if the lithosphere were treated as a thin shell sphere subjected to an internal pressure. The illustration opposite shows this in a cartoon format as an aid to the understanding of the terms involved. If a thin shelled sphere is subjected to a high internal pressure and by definition a developed 'vertical force', the area of maximum stress would be along the diameter of the shell at right angle to the force. The area resisting this developed force is described by the thickness of the thin shell multiplied by the mean diameter.
The ‘mid-Atlantic’ ridge is in the vicinity of the area of greatest stress and where rupture would most likely occur. As the separation of the South American landmass from the African landmass to form separate and distinct plates has taken place over geological time scales, it may be reasonable to assume that the original rate of separation took place far more rapidly than as shown at present. The propagation of the crack that is now the mid-Atlantic ridge would have occurred after separation had taken place.
In a similar manner, the continuous movement of the position of the centre of mass with respect to the centre of rotation would have caused a corresponding change in direction of the rifts by the change in direction of the developed ‘vertical force’ component. It should thus be possible to correlate the changes of direction of the rifts with the movement of the centre of mass and in doing so also determine the change in inclination of the principle axis of rotation
As the movement of the centre of mass from the centre of rotation is of the order of 0.5 to 1.0 Km, or 0.015% of the Earth’s radius, the actual magnitude of the movement is very small and totally feasible. The effects as shown by the analysis are however substantial
Consideration of the calculation in Appendix 3 shows that the centrifugal force at the equator will cause a 0.34% reduction in the gravitational force experienced as compared to that experienced at poles where the rotational velocity is zero. This difference is considered sufficient to cause the plates to move around the Earth on a frictionless surface. However as the friction at the crust/mantle interface will impede this movement, it is not unreasonable to see this differential force (from the equator to the poles) make itself manifest as ‘transform faults’ which are in the direction of rotation and are at right angles to the direction of the mid – Atlantic ridge 8,9 et al.
In a similar manner the transform faults in what are now almost extinct rifts should give an indication to the changes over geological time to the inclination of the principal axis of rotation.