as you'll see when we go inside in a minute,
we were hoping for limestone but in there is just shale.
And shale is not quite completely competent rock.
Competent rock is rock that will hold itself up without any shoring.
The shale would like some shoring,
and so parts of it are caved in in there.
That's Ben Roberts from -- he's the bat specialist from the National Park.
But there are many wonders back in there, like this weird fungus
on some of the collapsed timbers.
OK, here's another mine that's up on top of the property,
and it dates back to 1870.
That's what the property was originally built around --
it was a set of mining claims. It was a very productive silver mine.
In fact, it was the highest-operating mine in Nevada,
and it ran year round.
You can imagine what it was like in the winter at 10,000 feet.
You may recognize a couple of the miners there.
There's Jeff Bezos on the right and Paul Saville on the left looking for galena,
which is the lead-silver thing. They didn't find any.
They both kept their day jobs. Here's the last mine.
It's called the Bonanza Adit. It's down in a canyon.