Twenty-five million years ago (Mya), a line of fire and molten rock cut through the planet’s crust – like Wildfire cut through the ships at Blackwater Bay – and separated the previously joined continents of Westeros and Essos. This spreading ridge is analogous to the mid-Atlantic ridge that was largely responsible for the breakup of Earth’s last super-continent of Pangaea. The most striking evidence of this breakup is the morphological similarities of the shores of Westeros and Essos, appearing as though they could fit together as pieces of some geological jigsaw puzzle (similar to Alfred Wegener’s, and others’, observation that South America and Africa seemed to fit in the same way). Based on the average spreading rate of the mid-Atlantic ridge (~2.5 cm/yr), we calculate that the rifting between Westeros and Essos began around 25 Mya.
Furthermore, we propose that the Mountains of the Moon and the Hills of Norvos all belong to the same range, preferentially eroded in the east for reasons unknown (more on this later). Also intriguing is the fact that the Hills of Norvos do not follow the same southwest-to-northeast trajectory as the Mountains of the Moon. We cannot say for certain the orientation of the fault that created these ranges, but if they once befell a more linear path, then we can surmise that the Hills of Norvos have rotated in a clockwise direction, indicating that the rift between Westeros and Essos began in the north, and effectively “unzipped” to the south. As of this writing, we cannot say with any certainty what caused the rifting (note: such radical changes in plate motion and the type of faulting can be found in Earth history, but generally require 100s of millions of years to come about, nearly 10 times longer than the process appears to have taken on this planet).
Perhaps the most controversial of our assertions is that plate tectonics are actively transforming the surface of Westeros, indeed the entire planet, and have done so for eons. Yet the very presence of mountain ranges, a breathable atmosphere, and even life itself suggest that active tectonics must be considered in all analyses of Westeros. Plate tectonics is the fundamental principal by which we understand Earth’s geology. Among many others, tectonics explains how continents move, how rocks help regulate the atmosphere, and how earthquakes shake the ground and volcanoes ignite the skies. Given active tectonics, we are somewhat troubled by the lack of earthquakes and volcanoes throughout the Seven Kingdoms. While we cannot be certain, it is possible that the faulting responsible for creating the mountain ranges has since stopped, or at least slowed to a point when the recurrence intervals of large earthquakes and/or volcanic eruptions is long enough to circumvent the written records. Though, at the moment, this remains speculation.