I can only imagine what the whole experience must be like. Too bad you can't be there overnight. I think I'd need weeks to explore that area.
Your description of the stone answers some of my questions. I'm not familiar with tuff, but I see it's also connected to volcanic activity, the same as pumice is. Several sites I've looked at are basalt, which is also supposed to be volcanic. I tend to look at chemical compositions of stone, so I'm wandering into that here. The fact you say it reminds you of old decaying concrete made me think of St. Martin's, New Brunswick. There are stones embedded into a soft sandstone in a similar manner, although much denser with the number of them. Reminded me of masonry or concrete the way you described.
Never would have expected to find hoodoos in BC, that's a badass looking shot and place. Do you have any idea how remote the place is where that shot is from?
I stumbled on that by accident, due to our conversation, lol. This one is located in northern British Columbia, about three quarters away from the US border and very close to the coast. It's very isolated from what I see and supposedly the area is covered with glacier for a large part of the time.