Tolkien's mythology of Middle-earth contains several world-destroying calamaties that are meant to reshape the geography of Middle-earth. The maps in the Ambarkanta show that he was interested in how these changes would affect the world on a global scale, and also that he has at least some interest in connecting his maps with a real map of the modern world.
For anyone not familiar with the maps in question, they may be viewed here:
The Ambarkanta maps refer to a set of five maps and diagrams drawn by J.R.R. Tolkien and associated with his work "Ambarkanta: The Shape of the World" (a text attributed...
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The first calamity is the destruction of the Lamps. The maps in the Ambarkanta show that large inland seas formed where once there had been giant pillars holding up the Lamps. There are also 4 very symmetrical mountain ranges, suggesting that the mountains of Middle-earth are constructed by the Vala Aulë during the creation of the world. One exception to that would be the Iron Mountains in the north, which are raised by Morgoth as part of his fortifications. Cuivienen and Hildórien, the first birthplaces of Elves and Men, respectively, are marked on this map as well.
The next calamity was the War of the Powers, in which Utumno was broken and Morgoth was chained. The general impression is that the shape of the world was altered in this conflict, and it was a significant enough disaster as to discourage the Valar from ever doing that again. The symmetry has been lost - geological forces are at play, and Middle-earth has taken on a new form.
There is a small change to the map after the alteration of the lands and prior to what comes after - Tol Eressea is moved across the Sea, leaving behind the Isle of Balar to show where it originally stood. The next world-changing event is once more brought on by the Valar, who raise the Pelóri higher and fence out the Noldor with the Enchanted Isles, etc.
We see Beleriand in the upper left of the Ambarkanta maps. Next we see of it, it looks like this (1930's map by Tolkien):
...which is based on a late 1920's map that looked like this:
The Blue Mountains of the Ambarkanta Map IV are shown on the far right of the 1930s one. Rather than showing the
formation of the mountains, Tolkien seems to be focused on portratying the deformation of an otherwise neat line of mountains. His landscape has shifted...but not due to plate tectonics, per se.
The War of Wrath at the end of the First Age results in the drowning of Beleriand. Most of what is visible here sinks beneath the waves. Several high points survive as islands - Tol Morwen, Himring/Himling, and Tol Fuin. The island of Númenor also appears for the first time, raised by the Valar.
(Image by Didier Willis, 2014)
(image by Jef Murray)
The next cataclysmic event is the drowning of Númenor, in which the flat world is made round. We don't really know the details of what effect that had on the geography of Middle-earth. There is some further drowning of the coast of no-longer-Beleriand-but-now-Eriador. The remnants of the Blue Mountains of the other maps are on the left side of this one. I chose the 'annotated' map, because the notes of Pauline Baynes and J.R.R. Tolkien show that they were thinking about latitude and what plants and animals would grow in the various places. These aren't the details of someone who is indifferent to geography!
It is (somewhat) possible to overlap the maps of Beleriand and Eriador:
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