As this tunnel continues, Jacob descends horizontally through a blasted unnatural tunnel, which points towards the very lowest part of the cave. Water drips from an open faucet somewhere. He is looking for the lightswitch.
Garden of Eden Cave:
Jacob walks without stop through the desert's dark cone, to arrive at a place higher than the flat floor. This is the entrance to the Garden of Eden Cave, portico to the land of the Dead.
Jacob travels through harsh rock, actually through the elevator, and arrives at the rotating door entrance to this world. After a short snack, he walks past the pay phones and into the dark.