Eastern and central Sakha comprise numerous North-South mountain ranges of various ages. These mountains extend up to almost three thousand meters in elevation, but above a few hundred meters they are almost completely devoid of vegetation. The Verkhoyansk Range was extensively glaciated in the Pleistocene, but the climate was too dry for glaciation to extend to low elevations. At these low elevations are numerous valleys, many of them deep, and covered with larch forest, except in the extreme North, where the tundra dominates. Soils are mainly turbels (a type of gelisol). The active layer tends to be less than one meter deep, except near rivers.