A mountain is defined as land rising more than 300m above the surrounding landscape. A mountain range refers to a group of mountains standing together. When many ranges are found together, they form a mountain chain. The Himalayas are located in Asia. As altitude increases, the air becomes thinner. The Mid-Atlantic Ridge is made of underwater volcanoes. Broadleaved trees are found at the foot of mountains, while alpines are found in the alpine zone at higher elevations. Mountain plants grow slowly due to harsh conditions.