Doh! Of course Turin died before his mother. Although I'd forgotten those Hobbit and Elven graves. The perils of posting without the books to hand.
At least its always guaranteed here that a knowledgable Downer or two will come along to complete the picture.
And, to take my part in doing so, I will mention Balin's tomb in Khazad-Dum. The Dwarves too appear to have taken the time to mark the graves of their dead when they could, even under the stressful circumstances that the last survivors of Balin's party must have endured.
The point remains, though, that only the mortal races seem to have "celebrated" death by marking the graves of their dead. Then again, maybe we just never hear of the cemetary just behind the Last Homely House.
