[Affric]

Upper is literally higher up with respect to distance from the Earth’s centre of gravity.

When I was 8 or 9 in school we studied Egypt and I had to know and no one could answer. Might have been one of the first things I used Google for.

[pyuser583]

Isn't Earth's center of gravity at it's core? Isn't all of the Earth's surface "upper" to it's center of gravity?

[Affric]

Altitude, way rivers flow