Mountains don't have a precise definition, but they are landforms that rise considerably around the surrounding landscape. Whether something is called a mountain or not can often vary from region to region. Mountains can form when plate tectonic processes, for example, when two plates collide and smash together, as in the case of the Himalayan mountain range. Mountains can also form from volcanic processes, such as Mount St. Helens. Mountains have varying ecosystems moving up their slopes, with some life adapted to the high mountain environment. Read about the latest studies about and exploration of mountains and their environments below.