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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.

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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.

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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?

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  • I don't have the caving expertise to answer this, but I would say that Leave No Trace principles should be carefully considered before doing something like excavating a tunnel in a cave. Beyond the ethical considerations, there may be legal implications if it's in a protected area.
    – nhinkle
    Jun 11, 2015 at 3:24
  • @nhinkle It's a provincial forrest cave, you have to travel into the backcountry on 4x4 roads then hike up above the treeline to get to it. It's unregulated for the most part as far as I understand, user maintained. We had to do some spring cleanup at the creek crossings just so we could make it to the trailhead.
    – ShemSeger
    Jun 11, 2015 at 3:49
  • @ShemSeger would be worth adding mountain / forest tags. As then it leaves coastal caving open for a new question as well - tidal caves pose different dangers :)
    – Aravona
    Jun 11, 2015 at 5:22
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    Scree can be very unstable. You don't want to dig a big hole, climb into it only for it to fill up again, with you in it. At the best this would likely be an Sisyphean task you'd spend lots of time an effort digging it out, for it to simply fill back up again!
    – user2766
    Jun 11, 2015 at 8:23
  • Paul Lydon might answer! @PaulLydon
    – WedaPashi ♦
    Jun 12, 2015 at 11:58

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In the UK and at least some other European countries, it is very common to dig in caves to get through blocked passages. Normally this is done through either sections of cave blocked by boulders from ancient roof collapses or through sediments left from post-Ice Age flooding.

For example, this photo looking upwards to the caver at the top of a dig currently ongoing locally to me, where cavers are removing boulders in the floor of a large room (or chamber) by following a wall downwards and shoring the boulders on remaining sides with scaffolding and boarding:

enter image description here

Old records mention ongoing passage somewhere lower down in the room (chamber) and they are hoping to gain access to this.

You are correct in that the problem is movement of the scree rather than dangers of walls or roof collapsing.

Your example would have to be treated as an exercise in removing scree and then somehow preventing the cavity from being re-filled afterwards by more scree. Unfortunately it seems to be a very difficult problem in this case due to the long length of sloping cave passage and the amount of scree involved. I imagine you would need a major engineering project for a permanent solution.

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  • And not to be the eco guy, but the huge pile of scree exited from the cave will have to be piled up somewhere.
    – Eric
    Jun 13, 2015 at 14:58
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    @radpin The caves are at 2200m, any scree you shoveled out of them would just tumble down the mountain and blend in with the scree slopes. No one would ever notice, especially after one winter when it gets smoothed out and new scree falls off the mountain and covers it up.
    – ShemSeger
    Jun 13, 2015 at 17:19

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