Answer:
I build up castles. I tear down mountains. I make some men blind, I help others to see. What am I?
I can climb mountains, cross streams, handle hundreds of feet each day, yet I never move. What am I?
The more you take, the more you leave behind. What are they?
I am a red drum which sound without being touched and grow silent when I am touched.
I am lighter than the material I am made of. You see parts of me but more of me is hidden underneath.
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.