the dunes at the beach, three layers, water, sand dunes, and trees atop them.
the sandunes disappear first, then the trees. if it was flat, they would both converge at the sea level with straight lines (with some irregularities because the beach isn’t a straight line).
and that’s just one way. with zero tech, or even measurements.
You don’t even need technology. You just need to get out of the city and out of a car and look at some far away mountains on a clear day.
the dunes at the beach, three layers, water, sand dunes, and trees atop them.
the sandunes disappear first, then the trees. if it was flat, they would both converge at the sea level with straight lines (with some irregularities because the beach isn’t a straight line).
and that’s just one way. with zero tech, or even measurements.