New Defender's Study Bible Notes
2:10 out of Eden. The geography described in these verses obviously corresponds to nothing in the present world, although some of the names sound familiar. The Noahic Flood was so cataclysmic in its effects (note II Peter 3:6) that the primeval geography was obliterated, with the post-Flood continents and oceans completely different.
The similarity of certain names (e.g., Ethiopia, Euphrates) is best explained in terms of the ascription by Noah or his sons of these names to postdiluvian features which reminded them of antediluvian geographic features, just as the explorers of America often gave European names to American sites.
2:10 four heads. The rivers described in this section could not have derived their waters from rainfall (Genesis 2:5), and so must have been fed by artesian springs, or controlled fountains from the great deep. This implies a network of subterranean pressurized reservoirs and channels fed from the primeval seas and energized by the earth’s internal heat (see notes on Genesis 1:9,10).