The geology of Game of Thrones

Image Map

This is Westeros as it exists in the days of tumult, in the days following the death of King Robert Baratheon, in the shortening days that warn that winter is coming.  But this is also the geologic history of Westeros, reaching far deeper through the annals of time than the reign of any of the Seven Kingdoms.  We pieced this geologic history together from character observations, town names, official Game of Thrones maps, and the principles of geology learned here on Earth.  Using only limited data we were able to reimagine 500 million years of planetary evolution, including volcanoes, continents rising from the oceans, and ice ages (with guest appearance by white walkers and dragons).  To explore the history, and to view our maps of the geologic reconstructions, click the numbered icons on the map, or on the links below.

Geologic events occurring XX million years ago (Mya) on Westeros:
(today) The size of the Game of Thrones planet
(25 Mya) The Earth split Westeros from Essos
(30-40 Mya) When Dorne boiled
(40 Mya) Land of ice
(60-80 Mya) The rise of the Black Mountains
(80-100 Mya) As the Moon rose, so did the Lannisters
(300 Mya) Diving the tropical reefs of Winterfell
(450 Mya) The sand ran red
(500 Mya) The first mountains
(2,000 Mya) Can you find it?

Attributions:
The geologic map of Westeros was created by Miles Traer.  The geologic history of Westeros was written by Miles Traer with the help of Mike Osborne.  Additional scientific details were provided by Hari Mix.  Game of Thrones is copyrighted by George R.R. Martin.

Acknowledgements:
All of the maps created for this project are based on maps created by Jonathan Roberts, Tear, and theMountainGoat.  Certain artistic details (such as mountain ranges) have been copied and adapted to suit the needs of the geologic reconstructions.  Without these detailed and artfully drawn maps, little of this project would have been possible.  Many details regarding the history of Westeros and the various rock types found on the continent are provided by “A Wiki of Ice and Fire.”

Building the geologic history of Game of Thrones

Ever wonder what Westeros looked like long before the Starks, Baratheons, Lannisters, or Targaryens roamed its surface?  How far back can we really imagine the history of the Game of Thrones planet?  According to Generation Anthropocene producer Miles Traer, we can look back through 500 million years of history if we apply geologic principles learned here on Earth, and a little imagination.  He has even made a detailed geologic map to prove it.  In this episode, producer Mike Osborne talks with Miles and gives a brief tour of the map, details how it was pieced together, and explains why the project isn’t quite as ridiculous as it seems.  So brandish your swords, tame your dragons, and stay well clear of the white walkers as we explore the geology of Game of Thrones.


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Westeros today, and the size of the Game of Thrones planet

Westeros today. Click to enlarge.

From the texts, we know that the kingdoms have persisted for thousands of years, with many kings rising and falling as the tides (though we won’t concern ourselves with kings or kingdoms here).  From the same texts and carefully surveyed maps, we also know that Westeros contains mountain ranges, hot springs, granite, gold mines, deserts, ice walls, and red, grey, and black stones used to construct castles.  To the carefully trained eye – admittedly trained here on Earth – each of these elements betrays a rich and complex geologic history of the continent, reaching back over 500 million years.

We began with a simple question: what is the size of the Game of Thrones planet?  After all, understanding processes at the planetary scale is crucial to geology.  Past researchers have attempted these calculations without consideration of the coupled system of climate and geology, and these are essential initial attempts.  We started with the most basic of observations: it is cold enough in the north to maintain the Wall of ice that shields the continent from the White Walkers, and it is warm enough in the south that the maps are colored as deserts, an environment encountered most recently by the Khaleesi, Daenerys Targaryen, at approximately the same latitude on Essos.

Hadley Cells, creating hot, arid, barren landscapes since forever (Via Wikipedia Commons)

On Earth, deserts appear within a general latitude range, with most near 30° north (for example, the Sahara in Africa) and south (for example, the Atacama desert in South America).  This is due to circulation of atmospheric Hadley cells.  The harsh cold of the north, and the presence of the Wall for millennia, suggests that the Wall is at or near the Arctic Circle, currently at 66.5° north latitude on Earth.  So we have some approximate bounds for Westeros, stretching from 30° to 66.5° latitude, and all of it likely on the northern hemisphere.  Finally, we have it on good authority that it is 3,000 miles from the Wall to the southern flank of the continent, the deserts of Dorne.  Using simple geometry, we calculate that the radius of this dragon-inhabited planet is 4,297 miles, slightly larger than Earth’s radius of 3,959 miles, but still remarkably similar.  Fortunately for us, this won’t be the last time we assume similarities between this planet and our home on Earth.

(next) The Earth split Westeros from Essos –>

The Earth split Westeros from Essos – 25 Mya

Westeros 25 million years ago. Click to enlarge.

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.

Dammit mid-Atlantic ridge. Why are you always driving a wedge between us? (via Wikipedia Commons)

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.

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