The Rocky Mountains are rugged glaciated mountains as high as 14,000 ft (4,300 m). Many high-elevation plateaus composed of dissected, horizontally layered rocks lie in Wyoming and Utah.  The climate is a temperate semiarid steppe with climate influenced by the prevailing west winds and the general north-south orientation of the mountain ranges. A striking feature of the region is its pronounced vegetational zonation, controlled by a combination of altitude, latitude, direction of prevailing winds, and slope exposure. The uppermost (alpine) zone is characterized by alpine tundra and the absence of trees. Directly below it is the subalpine zone, dominated in most places by Engelmann spruce and subalpine fir. Below this area lies the montane zone, characterized by ponderosa pine and Douglas-fir. Grass, often mixed with sagebrush, regularly covers the ground in open ponderosa pine forests and some treeless areas. Below the montane belt is the foothill (woodland) zone.