Like others mentioned, having the dwarves build impressive terrasses on the mountains and growing food/herding animals up there makes sense. The more well off mountainholds establishing true feats of engineering in the style of Machu Picchu, Petra or the Himalayan monasteries in the mountainpasses. Fits with the theme of dwarves being great builders and engineers as well.

Lower class dwarves are then those that work these farms, whereas the rich and powerful live safe, content lives deep in the holds (but way above the mines). As another addition, you could probably toss in "sunkissed" as a dwarven slur for those that dwell in the sun (like lowerclass dwraves and elves)