Geothermal Valley - Path to the Ridgeline Base Camp

After escaping the FLOODED ARCHIVES with the Atlas, you emerge from a tunnel onto a ledge overlooking the valley. There's a survival cache (17/20) buried just ahead, near the right wall. Dig it up. Then follow the path to the northwest.

Follow the path to the north and you'll meet a Remnant sentry looking out over the valley. When you're done talking to him, crack open 2 salvage crates—one near where he's standing...

...one beneath the elevated wooden platform.

Then use your grapple axe to climb onto the platform...

...to find a document (30/33), The Remnant from the Diary of the Resistance series (Greek).

Drop to the ground, grapple swing across the gap with the broken footbridge, and continue along the path, gathering various supplies along the way.

There's hardwood (not shown), feathers in a nest sitting on a branch above the path, a salvage crate on the ledge to the right...

...and a container with cloth or herbs and possibly a few gold coins on the left.

Continue along the path to a stream. On the far side, to the right, is a rock ledge with another survival cache (18/20). Ahead on the left is the Ridgeline Base Camp, and Jonah is waiting just behind the rocks on the right.

IMPORTANT: Approaching Jonah triggers a cutscene that will carry the story forward and prevent you from returning to the valley for a while. So, if you want to explore the Geothermal Valley, AVOID JONAH FOR NOW. Then, when you're ready to move on, return to the stairs leading up to the tower and talk to him. If you accidentally trigger the cutscene, don't worry. You'll be able to return to the valley later via fast travel.