About the Mountains biome
The Mountains biome is an uncommon biome that includes huge elevated peaks, covered in snow. Grass and trees do not grow naturally in this biome due to the thick layer of snow. Under the snow lies stone. You also won't find any water nor sand.
This biome is not recommended to start a Colony, as it's steep peaks and lack of resources makes it hard to advance. Another troublesome issue with a colony in such a daring place is how long the zombies take to reach you - making a colony so high up will have you facing an endless flow of zombies coming up the mountains.