but the Mediterranean is a sea.
Well, you got me there. I guess I wasn't paying attention to what I was writing...
Or it could be an accurate representation of what the world looked like at the time of the map's creation. I'm somewhat amazed that this possibility has escaped everybody thus far. After all, we're dealing in lost civilizations and pulp adventure, here.
It didn't escape notice -
In other words the tablet is both a clue to what is relevant and is a device which by it's very nature dismisses those things which you cannot yet use to make any deductions about it's true nature. The map is not the rhetorical territory.
Therefore the only real evidence at hand is the tablet itself.
The tablet is itself.
Think in that way.
Dismiss at this point what you cannot yet know and instead concentrate on what is known.
In other words you have to use what you do know, not what you don't know.
It is resolvable in that fashion.
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Assuming that is Italy, where is the Atlantic Ocean and where is the rest of the Mediterranean Ocean?
And why do the land masses look like that?
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My immediate thought is that, for many ancient civilisations, the Mediterranean was the whole world (which they thought to be flat). The writing round the edge, cutting off the map, reinforces the idea that the map is not so much a representation of a specific area as it is of the whole world. The X, being at the centre of the map, therefore symbolises the middle of the world. And since we now know that the Earth is a globe, we're looking at the centre of that globe.
That's one possibility.
And the center of the globe is a good idea, psychologically speaking. From the view point of how the map-maker saw the world.
But, if the map is as it appears then the outlines of the map do not show extended ocean, or seas, but the fact that the limit of the map are bordered by land. In other rods many ancient maps speculated that the Atlantic ocean was at one end of the world and whatever other limits were assumed at the other (though some maps simply concluded at whatever terminus was actually known) this map implies that land, not sea or ocean surrounds the central areas of the map. That the interest area of the map is completely encircled by land, not water. Any map maker proceeding in either direction, even one who was making a map from rumor would know the stories of seas and oceans extending in either direction to unknown limits, not that the Mediterranean was bordered by the enclosing land-limits which seem to be displayed.
And in addition the landmasses, although resembling Italy and northern Africa, are recognizable, many are obvious variations, and show much more land and land area than is common nowadays and much less water than is common nowadays.
Now assuming the point of the game is the idea of a Hollow Earth (those are the operating parameters upon which the game functions), and assuming that the map is ancient and there is nor reason at all to suspect that topographical and oceanic conditions were the same at the time of the map (graphic image) construction, then at least one of the mysteries is why is there relative to today so little water and so much land?
Another assumption is that the X marks a locale to which the party should head, and it may or may not. But that's not an assumption anyone should automatically make and it is certainly no mystery geographically because it is obviously marked. But it is not marked on a land-mass, it is obviously marked at sea, and if there is an underlying landmass, like an island, then the landmass is so small that the X covers over it, and if the point were to find the land mass it marked, then the X occludes rather than illuminates the point being described. It would be better and more useful to exaggerate a small land mass than hide one beneath a point that gives no real clues as to the real locale.
Not many great civilizations are built in the sea per se, they need an operational base. Assuming they are human or human like of course.
So the X might mark a passage to this ancient civilization, but one that would by its' very nature be very difficult to reach unless it was near the surface (or instantly recognizable, that is a mighty vague clue as to real location), where men could reach it easily. Or it might mark a point where things from elsewhere were entering our world (from below or form some other means), or a navigational point, or a focal point, or a clue to a translation matrix, or some natural phenomenon that becomes evident upon approach, or any number of other things, including some biological organism or creatures. Or it could have been the spot of a big hole through which our seas and oceans drained into a "hollow earth" cavity and that would therefore account for the discrepancies between the landmasses and waters depicted in the map and those of our present era. The natural assumptions of the game demand that the idea of a hollow earth is reusable, that it is reachable (or else no adventure connected to it) and that some sort of intercourse or traffic occurred as a result, in at least one point in time. And in resolving any conundrum you always have to begin with the natural and most important parameters outlining whatever problem you are addressing. Regardless though, if there is a point of intercourse, then it will not likely be the obvious one in the obvious way.
But given this is an ancient map and that obvious geological changes have occurred since then and now then the chances of discovering what it is, no matter what it is, without further help seem to be slim. But that is not really our problem, our problem as originally construed is simply "what is the mystery central to the game as associated with the agency of this tablet?"
There are several possible mysteries associated with the tablet and the writing, though I suspect the writing is not germane to what the real mystery is or Nareau would have at least provided some clues as to what the langue is, or from what it derives, or something like that. As I said it is obviously not a modern langue (unless a forgery) and not enough clues were provided to decipher or translate it. And we do not know if the player will be doing the translation or the character will be, though we do know it is the character who has a background in ancient languages (we know nothing about the player's capabilities, other than some are smart), so it is translatable at least in game terms by a familiarity with ancient leagues and with some common alphabet (though this could mean a real alphabet or was just a term of convenience Nareau was using to make a point.) But since Nareau did not explain what language, alphabet or what he meant by these terms, it is very unlikely that the script is the real mystery or even the real clue to the real mystery, or he would have given us that information. Because how can he expect us to understand the mystery if we have less information than his players have and he expects them to find it difficult, perhaps even too difficult? So the script is not germane to the mystery per se. (the script cannot possibly translate directly into English unless the script is either a fake and forgery and added later as a code that can translate directly into English, or it is an in-game trick. That is, the symbols really represent an ancient script, as they would in real life, but for benefit of the players the symbols magically translate straight into English once you recognize the alphabet and don't have to fool with foreign words, letters, phrases, etc. For game purposes you don't have to translate anything but the alphabet, but in real life you would have to translate the real language, not just the alphabet. A hieroglyphic bee would not be an English "B.") So assuming the script does not magically transliterate or that it is not an encoded forgery then the nature of the mystery(s) lie elsewhere.
However the obvious, or one of them, graphic mystery is, where is all of the water? (And with less water more land is exposed.)
That is of course assuming this is Italy at some different point in time. The image could be in obverse and what we take as water actually be land, but by the way it is carved it does appear the water level lies below the land and so it does resemble Italy.
But my first questions would be, why does the world look different and what does that mean and how did it get that way and who represented it that way and for what purposes?
As for the script (and I think I know what it is and what it is doing relative to the tablet as a whole), which is obviously fashioned in three sections of encircling script, and as for the tablet itself, both are circular. And look at the break pattern. That is not a natural break pattern for most any kind of stone.
It was deliberately split in that way and that tells you other things too.
Among other things that it was split to be preserved and reassembled. It was not an accident.