Geology Observations

It is important to appreciate that the small Earth models presented here were constructed using published geological mapping. It is this mapping that dictates the precise crustal assemblage and Earth radius when moving back in time. On an Expansion Tectonic Earth it is also important to understand appreciate that Earth's geological history involves two primary phases; an initial, ancient supercontinental phase and a current, modern continental phase.

For the first 3,750 million years, extending from the early Archaean Eon through to the end of the Permian Period (pass your cursor over the Archaean to Permian time periods at left) the entire, much smaller, ancient Earth was covered in continental crust and was overlain in turn by a network of ancient continental seas. It was the distribution of this network of ancient seas that defined the configuration of the exposed ancient supercontinental lands. This entire phase involved an imperceptibly small increase in total surface area of the Earth per year, giving rise to a protracted phase of stretching and rifting of the crusts which were localised within a network of sedimentary basins.

The second phase of Earth history commenced during the late Permian Period, some 250 million years ago. At that time the Earth's crusts had reached a critical stage whereby crustal stretching and rifting was exceeded and replaced by crustal rupture and breakup of the ancient Pangaean supercontinent. This breakup then gave rise to formation of the modern continents and opening of the modern continents. The post-breakup history of this opening of the oceans is preserved within the seafloor crusts. (Pass your cursor over the Permian to late-Cretaceous time periods at left.)

The fundamental uniqueness of Expansion Tectonic small Earth models is that crustal plate assemblage is simple and predictable. By progressively returning the intruded seafloor volcanic lava back to the mantle, each remaining crustal plate can be reunited along their common mid-ocean-ridge spreading centres with a precision estimated to be better than 99% fit for each small Earth model. (Pass your cursor back and forth over the Permian to Pliocene time periods at left.)

Moving back in time, once all of the seafloor volcanic lava has been returned to the mantle, each of the remaining continents reunite precisely to form a single, unique, Pangaean supercontinent during the late-Permian Period on an ancient Earth at about 50% of the present Earth size.

Similarly, by returning eroded sediments deposited within sedimentary basins, along with intruded magmatic and volcanic rocks, back to the ancient lands and mantle respectively, the remaining network of continental sedimentary basins can be progressively closed on smaller Earth models. The remaining, more ancient crusts continue to reunite together throughout the Palaeozoic and Proterozoic times as one seamless supercontinental crust. (Pass your cursor over the Permian to Archaean time periods at left.)

After progressively removing all younger sediments and reducing the surface areas of each of the surrounding sedimentary basins back in time, the most ancient cratonic crusts are then shown to assemble together during the Archaean. The radius of this ancient Archaean supercontinent was about 27% of the present Earth, about the size of the present Moon.

It should be noted that because of the extremely low rates of change in Earth radius existing during the Precambrian times, the Archaean small Earth model shown represents about 2,400 million years of Earth history, representing over half of all known geological history.