I'm assuming you found the answer by now (or gave up), but it seems if you examine the rock pile before you find the pickaxe, it's bugged and nothing happens when you go back after finding the pickaxe. I had to load a save and redo it so that I found the pickaxe first before examining the rock pile.OK nm, I got out of the room, who would have thought you don't click on the door to open it.
Got another problem now though, in the cave, found the pickaxe, but can't use it when I try and clear the rockfall.