There are approximately 40,000 lakes in the Yana basin, including both alpine lakes formed from glaciation in the Verkhoyansk Mountains (lowlands were always too dry for glaciation) and overflow lakes on the marshy plains in the north of the basin. The whole Yana basin is under continuous permafrost and most is larch woodland grading to tundra north of about 70°N, though trees extend in suitable microhabitats right to the delta.