Dugby is convinced that he has discovered the ancient city Gorondia, and you can help him go there.
Clear the Tracks
Go along the tracks and destroy the boulders in the way. Then go back to Dugby's mine cart, attach a fan to it and put it on the tracks, then talk to Dugby and tell him it's ready. Stand in the cart and hit the fan.
Quest Reward
Dugby gives you a Large Zonai Charge.