What Am I Riddles

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

What am I?

Question: I am the only organ that named myself.What am I?

Question: I join you in battle, fist clenched tight.
We pound three times with all our might.
If my rival decides he will sign for peace;
I'll crush him, and the fight will cease.
But if he lays his hand down flat;
I'll suffer defeat, that is that.

What am I?

Question: My food and drink were left behind
by ancients from another time.
I grind my feet upon the earth
with strength come from a metal hearth.
My mind is trapped when I run free
when still, it wanders far from me.

What am I?

Question: 100 feet in the air, yet its back is on the ground.

What is it?