Lori, I love the last photo, like a marmot, poking their heads up above the rocks.  I haven't grown this fine plant but hope to one day.

I couldn't tell you the actual pH that groundwater in contact with the rock would have, but I would expect it to be pretty basic, as the rock in the photos is limestone, and limestone is exposed at surface over vast areas here. It's either the Palliser or Banff Formation (ouch, I feel I should know this... must get myself a map) which are both very thick and thus form extensive outcrops. The front ranges of the Rockies in Alberta are, in fact, predominantly limestone.   (The garden photo, however, shows what I jokingly refer to as my crevice garden, in which the rocks are siliceous siltstone, i.e. not calcareous.)  
A tarn is a glacially-carved lake, i.e. a lake in a cirque, often filled by snowmelt.  

I don't believe the plant is sensitive to pH, particularly, although that is something perhaps others could comment on.

Thank you!  I'll definitely try to collect seed... although, in last year's photos, I did not notice signs of pollination - no colour change in the flower eye - assuming that is reliable... ?

A few more photos of a lovely species, in the wild:
         


And in the garden - in bloom and showing its typically brilliant fall colour:
 

Yes, you have a sharp eye, Trond!  That photo is from Forgetmenot Ridge in Kananaskis, one of our favourite (though gruelling) hikes.  The highest part of the ridge is capped by a boulder field of quartz and chert pebble conglomerate slabs.  I'm embarrassed to say that I don't know what formation it is.  If there are any local geologists out there who know, please pipe up!
The conglomerate supports a fascinating growth of lichen - bright green and black, with some orange.  Walking through the boulder field about a kilometer or so out to the true summit is fun and interesting... must watch one's step to avoid twisting an ankle, though, and I imagine the lichen gets slippery in wet conditions.  
I'm describing the area along the crest in the upper left of this photo.  (NB.  I think may be the only photo of myself that I've ever posted here that's a close enough view to make out that I'm actually a humanoid.   )


It's a beautiful area, with views off to the plains to the east and of the mountain ranges to the west:
     

Thanks Lori, nice to meet you I love that kind of landscape although it is tough to the feet as you say.