A measurement of time found on a map

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

What am I?

Question: What do you call a sad bird?

Question: Where do all the letters sleep?

Question: What tastes better than it smells?

Question: What goes in the water black and comes out red?

Question: What loses its head in the morning and gets it back at night?