Riddle Me Tuesday: Edition 2

From treasure trove of Tolkien:

This thing all things devours:
Birds, beasts, trees, flowers;
Gnaws iron, bites steel;
Grinds hard stones to meal;
Slays king, ruins town,
And beats high mountain down.

Do you know what it is?

Riddle Me Monday

Simple! It’s Monday: I give you a riddle, you try to solve it!
(Hint Hint: It will deal with the themes of the previous week. Comment to guess the answer!)

But try do I to count that which
the human race’s future dreads
as little more than I can fathom
sideways blows the paper shreds.

Who am I?