Steeper and higher than mere hills, mountains are over 1,900 feet in elevation and typically have steep, sloping sides and rounded ridges and peaks. They tend to be rocky and barren above the tree line, and many mountains get significant amounts of snow in the winter months. They are formed when the Earth’s tectonic plates collide, pushing the crust of the planet higher, forming mountain ranges.
Some mountain ranges like the Himalayas are still growing, while others, like the Appalachian Mountains, are slowly diminishing under the forces of wind and rain erosion. Volcanic mountains, like Mt. St. Helens in Washington and Mt. Kilimanjaro in Tanzania, rise up from the surrounding flat terrain in dramatic splendor.
Mountain habitats vary tremendously from the lush, lower elevation foothills to the harsh, often barren, mountain summits. Atop alpine mountains, the temperature drops, the air thins, and the sunlight is harsh. While many different plant and animal species thrive in lower elevations, it is an unforgiving landscape above the tree line. However, some hardy species still survive at high elevations.