| "there are Tolkien's latest thoughts, his best thoughts, and his published thoughts and these are not necessarily the same." — Tolkien's Legendarium|
|This article is non-canon.
Thorn Sir ("Eagle-stream") was a river at the bottom of a gorge in the Encircling Mountains into which Glorfindel and the balrog fell into. After this battle the river was stained black by the balrog's blood for many days.
- ↑ J.R.R. Tolkien, Christopher Tolkien (ed.), The Book of Lost Tales Part Two, "The Fall of Gondolin", pp. 192-194