In the south, it was an east-west range that divided Dor-lómin and Mithrim to the north from Beleriand to the south, then in the east it curved around to the northwest, forming the boundary of Hithlum. A line of hills to the southwest formed the southern boundary of Nevrast, while the Mountains of Mithrim were a northwesterly spur that separated Dor-lómin from Mithrim.
Several rivers arose in the Ered Wethrin, including Narog, Taeglin, and Sirion. The easternmost point of the Ered Wethrin reached nearly to the Echoriath, forming a steep-sided valley through which the upper Sirion ran.
The Ered Wethrin disappeared beneath the waves at the end of the First Age.
- ↑ J.R.R. Tolkien, Christopher Tolkien (ed.), The Silmarillion, "Quenta Silmarillion: Of the Coming of the Elves and the Captivity of Melkor"
- ↑ J.R.R. Tolkien, Christopher Tolkien (ed.), The Silmarillion, "Map of Beleriand and the Lands to the North"
- ↑ (Note on the word *gwathren, note 3) at Hiswelokë (accessed 19 November 2010)