We could see the Seven Sisters in the far far distance - not sure if they are visible in the photo. But the COG is just on the right.
At the base of the cliffs there is concrete reinforcement and then a wide strip to catch bits of the cliff as they fall off.
When I say the cliffs are chalk - there is flint (and other rocks) mixed in, but the chalk that falls is pure, white, soft chalk. You can write with it, as I did here. For some reason I could only find a few smallish pieces of chalk mixed in (as noted), but at some points the pieces are pretty large.
The chalk cliffs are the product of some geological forces that I read about and then forget. But, I think it's enough to say that they were once at the bottom of the sea (hence the chalk). And, when you see the matching cliffs in Normandy, you understand very easily that at some point they were connected, but broke apart.
Just at the beginning of this Under Cliff Walk, there's an area called "Black Rock." It's brown, really, but there is a seam where the dark stops and the white begins. In the brown area have been found some of the most important signs of the early geology of the area, including fossils and a Neanderthal cutting tool.