Rubble, A Block for Archeology (Caves & Cliffs)

I'm not going to lie, hearing dirt and gravel slabs being thrown around after the initial showcase of the system has inspired this idea. That and the fact that dirt and gravel being the chosen sifting material would complicate things. Ruins within your world should have a custom, identifiable block to dust away, one I think 'Rubble' would be a fitting name for.

As long as its texture is different, it doesn't matter too much what it looks like as long as it's distinguishable from dirt and gravel but preferably still containing earthy tones and colors to fit the environment.

The (hopefully) many various randomly generating structures throughout your world need some way outside of average blocks to let you know there's a proper dig site ahead rather than something entirely else, and I think this is a good way to go about it.