Something has been bothering me for quite some time, to a small degree.
I think I have posted this somewhere else, but can't find it. Doesn't it seem like Abode is extremely stable from a geological standpoint? With the only exceptions being one real or imagined fissure in the wall of Blue Mountain that Brace held at bay, and the volcano near Sarrow's End, there is no evidence that there is much tectonic activity.
-Troll caves, dug in dirt, stone, sandstone, and whatnot don't shift. Tens of thousands of years later, the only thing that seems to affect them to show the passage of time are the mineral deposits. The tunnel from the Father Tree Holt up to the Frozen Mountains appears to be thousands of miles long, and about one troll wide, but other than the blockage the Trolls themselves placed to seal it, the passage never shifted.
-There is no sign of fossil fuels. I understand that this might be a result of artistic license, but for the sake of argument there is no coal, oil, geothermal energy sources, shale-oil, tar pits or other sources of energy or petrochemicals, etc anywhere throughout the timeline of Abode. We do see chemical rockets of unknown composition, and references to nuclear weapons, but I don't recall any references to gasoline. The only exception I can think of might be among the racing vehicles Scorch drives, but I can't recall anything more than that they had a mechanic working on them. I have no idea what the fuel was.
-While there is some reference to something akin to nuclear weapons (Trollclaws, IIRC) the Trolls don't use radioactive isotopes for lighting (as I wrote in my fanfics). Generally, it could be assumed that the weapons use fusion (light elements) and not disrupt the theory. On Earth, we only have such large amounts of heavy metals (materials that can be used to fuel reactors and whatnot) because of the large amount of tectonic activity churning the earth's surface up, bringing the heavy materials to the surface where we can mine them. On a planet without plate tectonics, such heavy metals would be too deep to be accessible.
The thing is, if there isn't any tectonics at work on the planet of Abode, there are some serious problems that can occur, or there is something very odd going on.
On our real planet, the gravity of the moon and the sun flexes the surface crust slightly. This generates heat which helps keep the interior fluid and keeps the tectonic plates moving "smoothly". I had read a theory (dunno how sound it is, keep in mind) that if we didn't have this effect the mantle and core would cool and possibly crack the planet or other not-nice things might happen. Just knowing the little I do about material science of solid objects cooling, either the solid must be kept warm, or cool so slowly that there is very little temperature difference between the outside and the inside, or the solid will crack (actually had steel shatter on me the other day in the quench tank!) If you have ever tried to make glass 'dragon's tears' and failed, you know what I mean.
A) Abode's sun is small and does not pull much on the planet (presumably the moons as well, as has been discussed elsewhere)
b) Abode is VERY OLD. Like old enough to be fearing the eminent demise of it's sun.
C) Abode is VERY small and was able to cool quicker with less effect of tidal forces from its sun. This would have a lot of interesting side effects, such as low gravity, and an explanation of how the various quest parties can travel from near the equator to near the arctic in a few weeks or even month on foot. This would also have some interesting effects on the moons, tides, and other things. One possible solution to the low gravity issue is if all the heavy elements settled out into the core of the planet and the planet is far more massive than it should be for its size.
This last option is making more sense to me as I type, as I think about the moon and how close it is to completely solidifying. The moon actually does have some tectonic activity: moonquakes and detectible lunar lava flow, but this activity is extremely low. The moon is actually off-balance (the dense core is not on center with its axis), which is what keeps one side facing earth at all times, and fairly low density compared to the earth in many of its structures. It doesn't show signs of cracking yet, though.
But a planet that had the mass near that of earth but a size slightly larger than the moon would be quite novel. Gravity would be that of earth, but outside gravity would not deform it as badly, I would think. Not as much leverage on material at the surface of a small planet as on a large planet. That's all my own thoughts and opinions, and I'm not even sure if that is technically possible.
One thing would be for certain, though: such a planet could not exist with large quantities of fissionable or unstable elements within itself. If, indeed, Abode is composed of heavy elements at its core, then they would have to be stable elements, or a chain reaction would occur like what supposedly happened on the (also fictional) planet of Krypton. This would make the core large and presumably composed of things like lead, gold, platinum, tungsten, bismuth (recently found to actually be unstable, all you Pepto-drinkers!), and whatnot above Radium.
What this would also imply to me is perhaps the planet's construction was the result of a very peculiar supernova-- one that produced plenty of stable heavy metals but few unstable ones. This would also mean possibly very peculiar composition of the dual moons.
In the end, what it comes down to is that the humans and Trolls (not the elves, they got their blasted magic to use to make up for a lack of technology! are severely handicapped in their progression of technology as compared to our real world.
I guess that must be why they took over 20,000 years to invent a light bulb.