1. Introduction

The observation of the uplifted but almost totally undisturbed Palaeozoic to Cenozoic meta-basalt and turbiditic melange³⁹ beds reaching the top of the Andes near Potosi in Bolivia (Fig 1a & 1b) prompted the investigation into both the origin and the magnitude of the forces capable of lifting the western side of the South American continent from below sea level to up to c. 6 km above sea level.

This treatise will attempt to demonstrate that forces needed over geological time, to sustain tectonic movements and the associated orogenic and metamorphic processes, are generated as a function of the rotation of the ‘wobbly’ Earth in which its ‘Centre of Mass’ (COM) is offset from its axis of rotation.

In doing so this analysis will also demonstrate that sea floor spreading, intrusion of magma into the oceanic crust and the formation of transform faults cutting the mid-ocean ridges are an inevitable consequence of the generated tectonic movements.

As such the convection currents in the mantle have mainly a passive rather than active role in tectonic plate movements.

A study of the dispersal, beginning in the early Jurassic, of the major continental plates that formed the Pangea supercontinent, to their present-day positions (Fig 2) clearly demonstrates that the movements in different directions have been continuously sustained over a time period of more than 200Ma. These movements have been mainly attributed to the ‘ridge push’ and the ‘slab pull’ forces proposed by Hess^1,18,53 - forces driven by convection currents circulating within the Earth’s mantle. Studies have also shown that centripetal and differential circumferential stress forces have not been seriously considered and have even been discounted^34,38 as a mechanism for tectonic movements. The general use of the term ‘inertial forces’ in the literature appears to include all the forces associated with the rotation of the Earth. The sustained movements towards both east and west, of the various plates away from the predominately central or ‘fixed’ African plate suggests that the forces responsible for driving tectonic activity could well be a function of the Earth’s rotational velocity.

It was noted that the ‘wobbling’ Earth, with its associated Milankovitch cycles, closely mimics the vibrational processional movements of an unbalanced rotating body in which circumferential stresses are induced at the outer rim. This approach is thus used to estimate the circumferential stresses induced in the lithosphere using the well-understood mathematical approach relating to unbalanced rotating bodies^{2,7, 26, 29}.

Furthermore, this approach allows for viable explanations to be given to describe:

• The northwards movement of Pangea in the Permian

• The start of its break-up at c.200Ma by the unidirectional plate movements from the essentially central and stationary African Plate in the earliest Jurassic eastwards and westwards

• The creation of the transform faults

• The probable reason for the nature of the topography of Pacific Basin oceanic crust west of the Hawaiian-Emperor volcanic seamount chain and

• An examination of the role played by ‘slab and ridge forces’ in tectonic movements.

This approach also helps to explain the creation, by the gravitational pull of the Sun, of the Earth’s rotation on a N-S axis and its tilt and precession cycles, about the ‘offset’ COM of the Earth. The Sun’s gravitational pull also drives the rotation of its other planets.

This in turn gives rise to a rational explanation of the reason for the rotation of planets (except Venus and Uranus depending on which is the north pole) in the same anti-clockwise direction as the Sun itself.

As Kepler’s laws (Appendix 6) clearly demonstrate, the Sun’s direct gravitational control of the orbital and rotational velocities of the planets on the unbalanced rotation of the Earth is given credence.

This is explained by the equation relating the circumferential force F acting on the crust to the radius of eccentricity E, where F = MRω²Eπ/4 where M=mass, R=radius and ω=rotational velocity.