Retreating glaciers from the last ice age smoothed much of the taiga land mass. High plains cover most of the area with some mountain ranges dotted throughout. As glaciers receded, they also carved a plethora of lakes, rivers and streams into the vast open stretches that cover most of the taiga biome. Mountains exist in the Taiga biome too. they are always full of snow from top to bottom. Some of these mountains are dormant volcanoes.