There are a lot of caves around where I'm from in the Southern Canadian Rockies, including the largest cave, and the longest cave in Canada, as well as the Booming Ice Chasm. The caves around here were carved out by the flow waters off of the continental ice sheet during the last ice age, so they aren't growing anymore, instead, they're filling back in.
Scree that falls off of the mountains finds it's way into the cave entrances, then slowly makes its way deeper into the cave, filling in some tunnels.
It's obvious in some places where the cave dead ends that it used to go further, deeper, or higher, but the tunnel is blocked by scree. Even though many are filled in, there's still water flowing into or out of them, so who knows how far they may go, or whether they may connect to other unexplored chambers or even connect to other nearby caves. Chances are good that the entrances to lots of undiscovered caves in the area are buried by scree too.
What I'm wondering is if there's any risks to excavating these tunnels? I don't think that they would cave in, they held themselves up just fine before getting clogged up with scree, I'm more concerned about digging up into the scree. There's one cave that may have a blocked entrance on the other side of the mountain it's in, which could be easily excavated from the inside out, but I don't know how much scree might be behind where we want to dig. I'm worried about an avalanche of scree pouring into the cave once we clear out enough of the tunnel.
How safe would it be to attempt to dig through some of these blocked passages?