There are four possibilities concerning the size of the Earth, which impinge on all theories of its global-scale tectonic evolution - a) its radius has remained constant through geologic time (the constant 'r' hypothesis underpins much past and current thought in the Theory of Plate Tectonics); b) its radius has increased with the passage of geologic time (the increasing 'r' hypothesis is the main proposition of the Expanding Earth Theory); its radius has decreased with the passage of geological time (an early idea put forward to explain the existence of the world's fold mountain belts); and d) its radius has fluctuated over geological time, sometimes increasing, sometimes decreasing (an idea put forward to explain the existence of both compressional and tensional structures in the Earth's crust). The first two parts of this paper deal with two of the above competing theories of global tectonics - a) the Plate Tectonics Theory in a globe of constant 'r', and b) the Expanding Earth Theory in which 'r' has increased over geologic time. Examination of these theories indicates that there are serious difficulties in reconciling the available geological data with the Plate Tectonics paradigm in which it is almost universally assumed that the globe has remained constant in size and the oceans constant in volume through geological time. Many of the inconsistencies disappear if the same data are viewed within a model of an expanding Earth, as long as appropriately sized globes are used for plotting up the data. The third section of the paper examines the periodicity of events in the lithosphere, hydrosphere, atmosphere and biosphere and relates these to episodic changes in the orientation of the axis of rotation of Earth which induce changes in the Sun/Earth relationship and the development of tremendous stresses and strains in the fabric of the globe, as well as other effects. The causes of such changes are thelmselves related to alterations of the Earth's fabric during Earth Expansion, principally due to unevenly distributed generation of oceanic crust at spreading ridges, which induces imbalance in the global gyroscope. The third part also looks at some of the secular changes that have occurred in various Earth systems, including the biosphere, hydrosphere and atmosphere. The paper ends with several major conclusions which attempt to explain the evidently close relationship that existed between events in the lithosphere, hydrosphere, atmosphere and biosphere.