5. The fundamental form of the GD12 glyphs can be described as a circle (or to be more exact an oval) surrounded by 6 'flames'. Each such 'flame' may be interpreted as a period equal in length to 1/6 of the circuit, e.g. 30 days with a solar 'year' defined as 180 days.

"... On the day when Tîstar produced the rain, when its seas arose therefrom, the whole place, half taken up by water, was converted into seven portions; this portion, as much as one-half, is the middle, and six portions are around; those six portions are together as much as Khvanîras ..." (Sacred Books of the East according to Jensen)

I suggest they meant this shape:

The six 'flames' equals the middle hexagon in area, which implies that the 'middle' is 'one-half'. Moreover, I suggest the middle hexagon is a region of 'water', whereas the six triangular forms represent 'land' (with the triangles illustrating mountains).

Consequently the earth should have an equal area of sea and land. This ancient idea still governed the travels of Captain Cook. So much sea had been discovered that there must be a continent somewhere in the south. He didn't discover the Antarctic continent, but had he done so and mapped it there still would not have been enough land.