The world of Adam was FLAT - first heaven or the garden of Eden - NOT our present earth. IF there were more than 4 rivers at the garden of Eden - Adam's world - then, the Scripture will indicate so... therefore, your assumption is based only on your own opinion and NOT supported by the Scripture.
To give you more ideas... Here are some model images of Ancient Hebrew Perspective of Flat Earth - simili- for reference only - Adam's firmament of heaven - surrounded by water below and above it - see link..... https://www.pinterest.ph/pin/113715959316206919/
Correct, the height of the mountain was covered at the height 22 1/2 - and the highest mountain is ALL covered with flood.... less than that height, the mountain could not been covered. Read again below....
To give you more ideas... Here are some model images of Ancient Hebrew Perspective of Flat Earth - simili- for reference only - Adam's firmament of heaven - surrounded by water below and above it - see link..... https://www.pinterest.ph/pin/113715959316206919/
Correct, the height of the mountain was covered at the height 22 1/2 - and the highest mountain is ALL covered with flood.... less than that height, the mountain could not been covered. Read again below....