[Revel]

I see no details as to how they were protected from the environment for so many years. Were they in a cave?

[blueplum]

according to this article from Science Alert, the panels were found on a large boulder (pix shown) that seems to sit out in the open.

Here is the 14-page research paper with detailed descriptions and photos of the several panels including the 'aerial' panel that likely required use of a ladder or ropes (click "full text: view' on the right hand side of the abstract to get to the paper)

3-d view of boulder from sketchfab