It's black dark inside the tunnel so it's only with the use of flash photography that you get to see what the rock actually looks like.
"you could have taken a torch"
"I said you could have taken a torch"
"yes, OK a torch would have been good"
Sorry about that interruption - It wasn't too bad today, but on occasion you walk through here with the constant dripping of water which always seems to, , , ,
"you could have drawn a picture of it"
"go on then, if you insist, I could have drawn a picture as well"
"why didn't you try chipping a piece off to have a look at when you got outside"
"are you finished or do you have any other suggestions?"
"no that's about it"
"right, fine, , , so apart from flash photography, taking a torch, drawing a picture and chipping a piece off, I think we're all agreed it's too dark inside to see what it looks like"