In Bereishit 2:10, scripture mentions the following:
10: And a river flowed out of Eden to water the garden, and from there it separated and became four heads.
11: The name of one is Pishon; that is the one that encompasses all the land of Havilah, where there is gold.
12: And the gold of that land is good; there is the crystal and the onyx stone.
13: And the name of the second river is Gihon; that is the one that encompasses all the land of Cush.
14: And the name of the third river is Tigris; that is the one that flows to the east of Assyria, and the fourth river that is the Euphrates.
It doesn't seem to be really adding anything useful--and completely out of context--to the previous topic, and the following topic. Why do we need to know about the four rivers?