Not all glaciers have this old bluish sheen I've noticed, some are fairly white, with layers of dirt and rock, others just white like plain snow, others like transparent ice cubes. I think this bluish ice is too icy, and I will try for more 'packed snow', with occasional patches of ice, or glistening layers. Fresh snow on top anyway, as this will probably be the case in the Ice Age.
So I've tried a different venue; no Photoshop mask anymore but a set of masks produced by distance shaders. And the glacier end will be lower, which is more appropriate than this wall of ice in my last tries. Here's the first try. The glassy stones are really weird, they need to shift. Will be continued...