This new biome would be known as the Crystal Pass (Sparkdew Pass? Crystal Mountains?). This would be a mountainous biome where the usual large forest was scattered with impassable pillars and cliffs of stone rising up from the ground. These large cliffs would be set back a bit from the open space of every glade and still allow for some expansion and woodcutting, but connections between a large number of glades would be through narrow passes. These impassable cliffs wouldn’t necessarily need to be large, rather they would just need to serve as an obstacle for the expansion of your settlement.
To provide a general theme for the Crystal Pass, a biome focusing more on rainwater could be interesting. Perhaps geysers could be more common in Crystal Passes, or there could be other buffs to rainwater collection/usage. Some thoughts just off the top of my head could be all rainwater related buildings (collectors and geyser pumps) having larger tank capacity or having a percent chance to not consume water in rain engines. For lore reasons, this could be due to the rainwater runoff from the mountaintops allowing villagers to make better use of it than in the ordinary forests.
To make up for the lack of wood in this biome, perhaps coal and sea marrow could be more commonly found. Perhaps all mined resources could be available (coal, copper, stone, clay, sea marrow) but there could be slightly less natural food? Just throwing out some ideas. I'm sure there is a way to determine a good resource balance when first making a new biome.
Overall, the biome concept is the primary idea. The special bonuses regarding the biome are just extra bits of information that could potentially fit.
A picture of what the starter glade may look like is included.