[Celebuial]

From reading The Book of Lost Tales I got the impression that the Silvan elves remained in Middle-earth but "faded". As Fingolfin II said, the fourth age was the dominion of Men, and I think that the elves kept their affairs to themselves and so became shadows of their former selves. I think that they became diminished and so all record and memory of them was lost. I'm sure that Tolkien explains it better. You should check out the book.