The last time I visited this place and took any photos before recently was about three years ago. The only photo I have of that time is this one: [link]
This is a six image stitch. I plan on returning in the fall!
This was my third recent visit, all within a week or two. I even went and found the little perch I took my old photo from for a taste of nostalgia. Really want to (am probably going to) spam you all with a bunch of photos of this place...because it really is one of my very favorites. It's called Little Buffalo River Falls and is almost directly on the Northeast border of Wood Buffalo National Park, NT.
The rock you see here is made up largely of what appears to be shale. There may be other types of sedimentary rock, such as limestone and sandstone. There are thousands of fossils embedded in many of these "tiles" that shed off the cliff walls. I have found a few myself...some slabs have an insane amount of shells and other imprints embedded in them! There are Brachiopod and I believe even Trilobite fossils to be found here, among others.
This region used to be covered by an ocean and these fossils are remnants of that. I've read they are about 400 million years old, from the Devonian period of the Paleozoic Era.