Good Riddles

Question: I'm a measurement of time.
But you'll find me on a map, not a clock.

What am I?

Question: Rob and Bob are arch enemies. They decide to have a fight to the death one day when a fairy appears. The fairy says it will give them both one wish. Bob wishes, "I wish for twice whatever Rob asks for."

What can Rob ask for to ensure he wins the fight?

Question: A trail, a union, together tied.
Come across me and you will find,
you cannot change the course I'm on,
without me you cannot travel on.

What am I?

Question: I have heard of a something-or-other, growing in its nook, swelling and rising, pushing up its covering. Upon that boneless thing a cocky-minded young woman took a grip with her hands; with her apron a lord's daughter covered the tumescent thing.

What is it?

Question: I'm round at the ends and high in the middle.What am I?