.. How do I cross the ravine?

There's a cable going across it.

But you can't hold onto it with your bare hands.

You need to slide across the cable.

But you need something with a pulley to slide down the cable with.

There's something like this in one of the shops in the central part of the town.

Have you visited the Voodoo Lady?

It's the door behind and to the left of the Citizen of Melee who sold you the treasure map.

The object in question is here.

Pick up the rubber-chicken-with-a-pulley-in-the-middle from on top of the chest inside the Voodoo Lady's shop, at the lower-right of the screen.

Use the chicken on the cable to cross the ravine.