So last time I managed to put up one of these posts, I discussed the nature of the great island (Not continent) of sunken Numenor, which might be only fleetingly familiar to the  fans only acquainted with Tolkien’s work through Peter Jackson’s film adaptations.

This time, however, we will be working on two much more familiar mountain peaks. Not only important, but the linchpins of both trilogies: Erebor, better known as the Lonely Mountain; and Orodruin, better known as Mt. Doom.

Across Gorgoroth by Ted Nasmith

Mt. Doom is relatively straightforward, geologically speaking. What gives it something of a twist is that it’s one of the few landmarks of the world that Eru Iluvatar did not make. Melkor, later known as Morgoth, summoned Orodruin into being during the First Age, and while Tolkien was quite adamant on Morgoth’s creative sterility, it stands to reason he could move some rocks around.

Orodruin, later known as Amon Amarth aka Mt. Doom, has all the tells of a stratovolcano. This kind of volcano is probably what you think of when you hear the term “Volcano”. Tall, conical, mad of hardened ash and magma, and prone to violent and explosive eruptions. Mount Fuji, Mount Vesuvius, and Mt. St. Helens are all stratovolcanoes.

So let’s take a look at the similarities.

Tall conical shape? Check

Infrequent powerful eruptions? Check

Burning hot internal magma chambers fit for forging rings of power? Check.

There is, however, one issue that we’ll see again in the Lonely Mountain: Where the hell is the water?

The creation of stratovolcanoes, generally speaking, requires the subduction of oceanic plates beneath continental plates. Which is to say, much like the other volcanoes I mentioned, Mt. Doom should be near an ocean if it’s meant to be a stratovolcano. The closest major open water, the Bay of Belfalas, is quite a ways away for it to be the source. I had to do some quick and dirt map comparisons for this, but Mount Doom is approximately five hundred miles from the open ocean. Mt. St. Helens is about one hundred miles from the Pacific, one-fifth of the distance. If anyone can cite me a source for a stratovolcano that far inland, that would be delightful.

In conclusion? Well, we’re going to have to do what the elves do best: Blame Morgoth (since Feanor can’t take the blame this time). That god of darkness clearly has as much respect for the laws of geology as he does for the laws of nature.

But we’ve still got another mountain to deal with.



The Lonely Mountain, center of the unimaginatively named “Kingdom Under the Mountain”, home of the dwarves of Erebor and later the dragon Smaug. It is known for two things: one, being a lone peak in otherwise relatively flat land. And two: Being full of gold and other riches. Enough gold, apparently, to lure a dragon in.

To explain the first, the most obvious first guess would be that  the Lonely Mountain is a Stratovolcano like Mt. Doom. That said, stratovolcanoes generally form along the boundaries of tectonic plates where you also often see mountain uplift. So how is it that the Lonely Mountain is lonely? Well, while we could try to chalk it up as an offshoot of the Grey Mountains, but those are hundreds of miles away with nothing but lowland between. Similar to Mt. Doom’s case, this leads to an issue in Erebor’s formation without an evil god to solve it.

Other possibilities remain, but none quite fit the MO of the Lonely Mountain, so that mystery might just have to be chalked up to Iluvatar (And Tolkien’s) dramatic license.

Next we move onto a slightly more complicated characteristic: The jewels and gold that makes the Lonely Mountain rich, with gold and diamonds in particular. And wouldn’t you know it, we get all of our gold and more than a few of our diamonds from the same process:

Via WIkipedia


While diamonds form through a number of natural processes, virtually all of the accessible gold on earth was brought here from meteorites, and quite a few diamonds were as well. So while I can’t offer a solution as to why Erebor is a mountain where none should clearly exist,  I think I can explain where its riches came from.



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