I uploaded high rez. zoom-ins of the lower corners of the map which show the solstice and sun positions.
When I showed this map to a friend, he said that this map isn't representing a flat earth, and that it's just another way of presenting a ball earth. But the solstice charts show the position of the sun and lighted portion of the earth. If this was representing a globe earth the chart would be saying that south stays dark all year round, which is not what modern science teaches.
(I also re-uploaded the main map above in full resolution. I know it can be found elsewhere on the internet, but there's definitely no harm in putting it in more places so more people can find it—along with the other pictures/reasonings I'm posting.)
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