Whimsies by Grundy  

Walm

“Elves!” Narvi laughed. “Always with the complicated theories when a simple one will do.”

“What then is your explanation?” Celebrimbor asked curiously.

“The Maker, when he had placed the Fathers where they would waken, realized Durin would need a sign to show them where he ought to begin his own work. So he tapped Barazinbar several times with his hammer. Wherever he touched, a stream sprang up to run down the Stair. And at the bottom of the stair, he stomped with his foot, so that the waters trickling down joined waters bubbling up, and so was the Mirrormere made.”