Driving down gravel road caused a loud metal on metal sound

What is your question?

Any idea what could cause this? i thought it might be a stone caught up in the brake somewhere but i cannot see anything without removing tire. its coming from passenger front tire in the brake area. it just started out of nowhere, car has like 30,000 miles on it so its pretty young still.

What makes this problem better or worse?

it doesnt make the sound unless the car is moving, with or without brakes applied

How long has your 2011 Volvo C70 had this problem?

just happened and i am afraid to drive it 30 miles to the dealer