From Tolkien Gateway
Thorn Sir ("Eagle-stream") was a river according to the early version of the legendarium in The Book of Lost Tales. It was located beneath Cristhorn, at the bottom of a gorge in the Encircling Mountains into which Glorfindel and the balrog fell. After this battle the river was stained black by the balrog's blood for many days. Its Qenya cognate was Eäsindi.
This river was later mentioned as Thornsir in the unfinished Lay of Eärendel, but was not used by J.R.R. Tolkien in any other text.
- ↑ J.R.R. Tolkien, Christopher Tolkien (ed.), The Book of Lost Tales Part Two, "III. The Fall of Gondolin", pp. 192-4
- ↑ J.R.R. Tolkien, "The Alphabet of Rúmil & Early Noldorin Fragments", in Parma Eldalamberon XIII (edited by Carl F. Hostetter, Christopher Gilson, Arden R. Smith, Patrick H. Wynne, and Bill Welden), p. 105
- ↑ J.R.R. Tolkien, Christopher Tolkien (ed.), The Lays of Beleriand, "II. Poems Early Abandoned: Fragment of an alliterative Lay of Eärendel", p. 142